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date: 20 January 2022

Space Law: Overviewfree

Space Law: Overviewfree

  • Francis LyallFrancis LyallEmeritus Professor of Law, University of Aberdeen


Space law is composed of disparate elements of ordinary national laws and general international law. It has been created by the agreement of states as to the international law that should govern important technical and technological developments of the later 20th and the 21st century. That agreement is expressed in five general treaties; other treaty-level measures including as to the use of radio, declarations of principle, recommendations on the conduct of space activities, and by state practice. The United Nations Committee on the Peaceful Uses of Outer Space (COPUOS), serviced by the UN Office of Outer Space Affairs (UNOOSA), plays a significant role in the development of the many aspects of space law, as do intergovernmental and nongovernmental agreements together with informal arrangements between space-active bodies.


  • Planetary Science Policy and Planning
  • Space Law

Space law is a major context within which space activities including planetary science investigations are conducted. That is not to say that other kinds of law, in particular civil law, are unimportant in the work of scientists, but the law relating to space now forms a separate branch of international law and as such affects the national law of states. Space activities also involve other legal elements such as national laws on corporate activity, insurance, contract and liability, not to mention the complex necessary national administrative provisions and procedures.

The title of this article is “Space Law: Overview.” It is written with the potential user of this encyclopedia in mind. So as not to get bogged down in semantics, crudely, a law of science deals with absolutes and cannot be altered, while a human law is mutable. What follows has little to do with the laws of physics that operate in the universe, although the practitioners of space law have to be aware to a degree at least of them because they affect the area of its competence.

Finally, in the ultimate although the traditional and accepted concept of “law” may require that what is prescribed is “enforceable,” in the area of space law what “law” dictates or recommends may not always meet that requirement. What is “enforceable” has varied over time. Compliant practice has been more important in the exploration and use of space.

What Is Space Law?

“Space lawyers” are concerned with more than strict law in the sense of enforceable rules. Space law is a conglomerate. Its ingredients include strict law enacted within sovereign states, rules agreed between states or within international organizations, and other practices and working arrangements arrived at among states, organizations, and those engaged in space activities. All govern or inform what those engaged in space activities do and form the civil context within which those active in planetary science work. Planetary scientists should therefore be aware of space law in its most general definition and, where appropriate, be willing to seek its development, extension, or modification.

Space law applies in outer space and to natural objects, including planets and asteroids within the solar system. It also has terrestrial aspects that are related to activities in outer space. A bundle of different laws and practices, it is a response to the technical and technological developments of the later 20th century, mutating as circumstances require. Fundamentally, it is founded on the agreement of states as to the international law that should govern activities in space. Its many aspects, not all of which may be obvious at first sight, may involve compromise between different objectives. National security considerations, commercial interests, intellectual property, insurance and the concept of the passing of risk, and other existing national laws can influence the negotiations as lawyers and advisers discuss and propose and diplomats and politicians debate how space law is to cope with its remit, the regulation of space (Dunk, 2011; Jakhu, 2010; Zhao, 2015). However, this article will not enter matters of national civil law (Smith & Baumann, 2011).

The Making of Space Law

While initiatives may come from a variety of sources, a major forum for and agency in the development of space law is the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS). An ad hoc committee from 1958 and set up formally in 1959 as a standing committee of the UN General Assembly, the 95 members of COPUOS represent an equitable cross-section of the 193-member UN. Its subsidiary bodies are the Technical and Scientific Committee and the Legal Committee. Annual COPUOS reports to the UN General Assembly are made via the Fourth Committee and appear in the Supplement Series 20 of the UNGA Official Records.

COPUOS is serviced by the UN Office for Outer Space Affairs (UNOOSA), the division of the UN Secretariat that promotes international cooperation in the peaceful use of outer space. Inter alia UNOOSA maintains the UN register of objects launched into outer space. It organizes space capacity building and educational programs; it also acts as the secretariat for various groups such as the Space Climate Observatory, the International Committee on GNSS, the Space Mission Planning Advisory Group, the International Asteroid Warning Network, and the Inter-Agency Meeting on Outer Space Activities.

International Law

As used in “international law” the term “law” has a number of aspects. It includes treaty provisions, custom, and, as some argue, practice. A treaty is an international agreement concluded between states and made in written form (Vienna, 1969). The normal process is that its text is agreed and signed. Thereafter the signatories must by their separate constitutional procedures individually and formally state their consent to be bound by the agreement, a step usually known as ratification. Signatory-only states are bound not to act contrary to the basic thrust of the treaty. Occasionally a treaty will provide that it has to be ratified by a minimum number of states before it can come into force. Sometimes a state will sign subject to a reservation, but the effect of a reservation cannot be to void the major purpose of the agreement. Normally only those states that have entered and ratified an agreement are bound by it. However, there are instances where a treaty articulates propositions of general validity, as is the case of elements of the Outer Space Treaty, and also instances where particular elements of a treaty become generally binding, having become part of international custom.

“International custom,” or “customary international law,” is more difficult to explain and in practice identify. It is not laid down, constituted, or articulated by any form of legislation. Similar to the concept of the unlegislated “common law” that is found in some legal systems, second to treaties, international custom is one of the sources of law to which the International Court of Justice (ICJ, n.d.), the supreme judicial authority of the international legal order, and other similar bodies look to find principles on which to decide a case or one on which it is asked to advise. Custom consists of a common international practice, entered into by states in the belief that compliance with it is obligatory. A state that persistently objects to such a common practice is not bound to comply with it, notwithstanding that the other states that accept it as customary law are so bound. Objection must usually be clear, or otherwise express, in order for it to be established.

International practice is how states in practice behave, but their doing so lacks the element that states consider compliance to be obligatory. In some cases an obligatory status can develop. Much depends on the views that states express as they comply with a practice. Thus, within the ambit of space law are the many arrangements agreed between space agencies but are not enforceable and lack any statement that compliance with that particular arrangement is compulsory.

Discussions of “space law” also include a variety of “declarations of principle” and similar statements, many of which originate from COPUOS, although other official and semiofficial bodies have contributed to their number. These contain principles and practices seen as desirable in the conduct of space activities, but which, while often complied with, are not “binding” in the legal sense—that is they are not enforceable through a formal procedure.

Finally there are the many practices of those engaged in space activities. Some are expressly agreed between practitioners in the form of memoranda of understanding, which may or may not be published. Some are unacknowledged in written form but can be observed to exist. Thus asteroids are named through the practices and procedures of the International Astronomical Union, a nongovernmental body. Again these practices are not enforceable through formal civil or criminal process.

All such practices and other nonbinding arrangements are generally known in international law as “soft law” (Marboe, 2012).

The Development of Space Law

Basic international space law developed very quickly, its speed dictated by need. Although there had been discussions among academics and others as to how outer space should be dealt with (Hobe, 2013), the appearance of Sputnik I in October 1957 put the question into clear focus. The United Nations General Assembly set up its Committee on the Peaceful Uses of Outer Space (COPUOS) in 1958. In 1961 (UNGA Res. 1721, 1961) and 1962 (UNGA Res. 1803, 1962) the UN General Assembly approved suggestions by COPUOS as to elements that space law should contain. These included that international law should apply off-world in space and on celestial bodies, that all states should have freedom to explore and use space, that there should be no national appropriation of outer space or celestial bodies, and that space should benefit all. A much stronger step was taken by UNGA Res. 1962 (XVIII) December 13, 1963, the “Declaration of Legal Principles Governing the Activities of States in the Exploration and Use of Outer Space.” Putting these ideas into treaty form was the next step.

The United Nations Space Treaties

Five treaties agreed over a 12-year period are the foundations of space law, the Outer Space Treaty (OST, 1967), the Agreement on Rescue and Return of Astronauts (ARRA, 1968), the Liability Convention, the Registration Convention, and the less successful Moon Agreement.

Outer Space Treaty, 1967

It took just over 2 years from the 1963 UN Declaration of Principles to negotiate the “Treaty on Principles Governing the Activities of States in the Exploration Use of Outer Space, Including the Moon and Other Celestial Bodies” which entered into force on October 10, 1967 (CoCoSL I, 2009; OST, 1967). This translates the basic ideas of the 1961 and 1962 UN Space Resolutions and the 1963 Declaration into treaty obligations, thereby removing uncertainty as to their legal weight. It is a universal treaty, open to all states (art. XIV.1). It applies to the space activities of individual states, to those of their nationals and national entities (art. VI), to joint state activities, and to those of intergovernmental organizations where parties to the OST are members (art. XIII).

It is important that the rights set out in the OST are rights of all states. They are not just rights mutually recognized as between the parties to the OST. Every state may explore and use outer space, authorize its nationals to do so, or utilize the services of non-nationals to provide and, perhaps additionally, to operate a space program for it. A space treaty of limited acceptance would not have been satisfactory. The concurrence of as many states as possible was more than desirable. It was necessary. In 1967 most UN members did not have space-faring capabilities, but they formed the majority in the Assembly. The options for their future had to be preserved. So the equality of all in the exploration and use of outer space was thus enshrined.

The first three articles of the OST catalogue fundamental principles. First there is the place of law. International law applies in space. That is assumed in Article I and made explicit in Article III (CoCoSL I, 2009, pp. 25–43). “Space” is not lawless, or a location free of legal constraint or principle. Second, “the exploration and use of outer space including the Moon and other celestial bodies” is to be “carried out for the benefit and in the interests of all countries irrespective of their degree of economic or scientific development and shall be the province of all mankind” (art. I, para. 1). Exploration and use are to be “without discrimination of any kind, on a basis of equality,” with “free access to all areas of celestial bodies” (art. I, para. 2), including for scientific investigation (art. I, para. 3). Third, there can be no national appropriation of space or of celestial bodies “by claim of sovereignty, by means of use or occupation or by any other means” (art. II). In that statement “occupation” is a technical expression used in international law on the acquisition of territory and involves both “being there” and the intention to act as sovereign in relation to the occupied location (Huber, 1928; Jennings & Watts, 1996). That cannot lawfully happen in space.

Celestial bodies are to be used exclusively for peaceful purposes. Nuclear weapons or weapons of mass destruction are not to be put into orbit or placed on the Moon or other celestial bodies (art. IV). Article V holds astronauts (undefined) as envoys of mankind to be given assistance in emergencies and, in case of accident, returned to the state of registry of their space vehicle. States are to report any phenomena that may endanger them.

Normally a state is not responsible for the activities of its “civilian” nationals. It is responsible for the acts of its officials only when they are carried out in an official capacity. However, OST Article VI lays international responsibility for national activities in outer space, whether by a governmental agency or by a nongovernmental national entity, on the individual state party whose national they are. Article VII then takes matters further, providing for liability for damage caused by space activities. A state is liable to compensate for damage caused to another state by its own space activities or by those subject to its jurisdiction, licensing, and supervision. By Article VIII states retain jurisdiction and control over space objects carried on their registry (see section “Registration Convention, 1976”) and over any personnel on board. A space object cannot be abandoned, and any found elsewhere than in the territory of its state of registry is to be returned to that state.

Articles IX, X, and XI call for cooperation and mutual assistance. Harmful contamination of the Moon and other celestial bodies is to be avoided, as are adverse changes to the environment of the Earth. States are to consult other states whose activities might be subjected to “potentially harmfully interference” by activities it proposes to undertake (art. IX). States are to “consider on a basis of equality” requests to observe the flight of space objects that it launches (art. X) and are to inform the UN secretary-general, the public, and the scientific community “to the greatest extent feasible and practicable” about the “nature, conduct, location and results” of their space activities (art. XI). Finally, Article XII provides for states to be able to inspect the facilities and equipment of others on the Moon, subject to due notice being given, maximum precautions to assure safety, and the avoidance of harmful interference with normal operations of the facilities to be visited.1

Acceptance of the OST is excellent. By January 1, 2021, 110 states out of a UN membership of 193, including all presently space-competent and space-active states, have ratified it and another 23 have signed but not yet ratified it. In short, the vast majority of the states whose interests are affected by the OST are parties to it, and the signatory-only states are bound by their signatures not to act contrary to its basic purposes.

Amendment of the OST is possible (art. XV), but amendments would be undesirable unless all parties accept them simultaneously. Space law, not to mention space activities, would not be well served were divergent versions of the OST to be law as between a variety of different states. The initial articles set out fundamental principles. Their integrity should be preserved. It is also hoped that no state withdraws from the OST, but should that happen its withdrawal would not exempt it from obligations in the OST that have passed into customary law (Lyall & Larsen, 2018, pp. 70–73).

There has been no formal objection to the OST. New states might consider it as among the “international law” that existed before they did, and hence they were not concerned in its making, but it is part of the legal system in which they exist. There is no real evidence of any “persistent objector” to the principles of the OST, let alone the emergence of contrary practice on the part of a state or group of states. Indeed, many consider the principles of the OST have passed into customary international law as state practice has fallen into line.

Rescue and Return (ARRA), 1968

The Agreement on the Rescue of Astronauts, Return of Astronauts and the Return of Objects Launched into Outer Space (ARRA) entered into force on December 3, 1968, just a year after the OST (CoCoSL II, 2013, pp. 9–82). ARRA is open to all states (art. 7.1), and as of January 1, 2021, had 98 state parties with another 22 having signed but not yet ratified it.

ARRA was a response to the already demonstrated uncertainties of space technology, the imminent increase in the activities of astronauts, and, potentially, the need for rescue. While OST Article V of the OST had included “rescue and return”—astronauts should aid other astronauts — as well as reporting dangerous phenomena, ARRA Articles 1–4 provide comprehensively for emergencies and the rescue of astronauts if necessary and their return to the state of registry of their space vehicle. The return of objects launched into outer space was called for by OST Article VII. ARRA Articles 5–6 provide more detail, requiring states to inform others of finding such an object or its component parts and to return it or them to the launching state at the request of the appropriate “launching authority.”

Liability Convention, 1972

That space objects might cause damage was obvious, but where should liability lie? In an appropriate instance national law might be invoked. Further, there is a long history in international law of the liability of a state for damage caused to another state and that reparation should be made for that damage. Space law is more explicit. The OST has a number of provisions regarding liability. The 1972 Liability Convention refines these. However, as this convention only binds its parties and has fewer ratifications than the OST, there is a quadruple regime for liability for space activities—that of the OST for its parties, that of the Liability Convention for its parties, one under normal international law, and, in appropriate instances, a remedy under a national law.

The Convention on International Liability for Damage caused by Space Objects entered into force on September 1, 1972 (CoCoSL II, 2013, pp. 83–226). By January 1, 2021, it had 96 state parties with another 19 having signed but not yet ratified it. Intriguingly, no provision of the convention prevents its parties from “concluding international agreements reaffirming, supplementing or extending its provisions” (art. XXIII. 2). Some recent bilateral agreements connected with the development of new spaceports make use of that freedom.

For the purposes of the convention, Article 1 defines the terms it uses. “Damage” is “loss of life, personal injury or other impairment of health; or loss of or damage to property of States or of persons, natural or juridical, or property of international intergovernmental organizations” (art. I (a)). Liability attaches to a “launching state,” which is a state that launches or procures the launching of a space object, and a state from whose territory or facility a space object is launched (art. I (c)). “Launching” includes attempted launching (art. I (b)), and “space object” “includes component parts of a space object as well as its launch vehicle and parts thereof,” including debris caused by the breakup of a launch vehicle (art. I (d)).

Articles II and III of the Liability Convention differentiate between absolute and fault-based liability. A launching state is “absolutely liable” to compensate for damage caused by its space object on the surface of the Earth or to aircraft in flight (art. II). In short, such damage must be compensated for without any defense available to the launching state. However, where a space object causes damage elsewhere than on the surface of the Earth to that of another launching state or to persons or property on-board, the launching state is liable only if the damage is caused by its fault or the fault of persons for whom it is responsible (art. III). That means, of course, that in-orbit accidents caused by orbital debris may well never be satisfactorily dealt with because of the difficulty in proving fault. Sharing these risks among those engaged in space activities would make logical sense, though it seems that idea so far has not appealed to actual participants in space activities (Sundahl, 2000).

Article IV deals with the case where damage is caused to a third state by the collision of two space objects belonging to other states. It is rather complex and need not detain us. Where two or more states jointly launch a space object, they are jointly and severally liable for any damage caused (art. V). A launching state may be exonerated from absolute liability to the extent that it establishes that the damage has resulted either wholly or partially by the gross negligence of or from an act or omission done with intent to cause damage on the part of a claimant state or its natural or juridical persons. Exoneration is not available where the damage has resulted from launching state activities that do not comply with international law (art. VI). The Liability Convention does not apply to damage caused by a launching state to its own nationals or to foreign nationals involved with the operation of the space object, or if they are by invitation in the immediate vicinity of a launch or a recovery area (art. VII).

Article VIII sets out the procedures by which a claim under the Liability Convention may be made. So far only one formal claim has been made, but it was settled without admission of liability (Cosmos 954, 1979). Claiming under the Liability Convention diverges in two major ways from the general rules of international law as to state responsibility. First, should the home state of a person or institution damaged not present a claim, another state may claim in respect of damage sustained in its territory by any natural or juridical person. Should neither the state of nationality nor the state where the damage occurred present a claim, then the state where the damaged person or entity is permanently resident may claim (art. VIII). Second, though they are not excluded, the Liability Convention does not require any local remedies to be exhausted before an international claim is made (art. XI).

It is unnecessary for the purposes of this article to enter into further detail as to liability or the settlement of a claim that is disputed through a claims commission (arts. X–XX). However, it may be noted that Article XXI makes special provision if a space object causes damage presenting a “large scale danger to human life” or “seriously interfering with the living conditions of the population or the functioning of vital centers.” All states party to the convention are, on request, to assist any state suffering such damage. That could happen were a solid space object to land with high velocity in a city or were one, powered by a nuclear device, to contaminate an area. On that possibility see section “Principles, Resolutions, and Declarations” as to the Principles on the use of nuclear power in space.

Registration Convention, 1976

The Convention on Registration of Objects Launched into Outer Space entered into force on September 15, 1976 (CoCoSL II, 2013, pp. 227–324). As of January 2021, it had 70 state parties, another three states having signed but not yet ratified it. When it was adopted, a procedure already existed for states to “furnish information promptly” to COPUOS “for the registration of launchings,” the UN secretary-general maintaining a public register of the data so transmitted (UNGA Res. 1721 Part B, 1961). That procedure remains available for states that have not ratified the convention. Information so submitted is published by COPUOS in the A/AC.105/INF series, available on the UNOOSA website. However, the Registration Convention provides two further mechanisms and requires more data than the fact of launch to be registered. When an object is launched into space, it is to be registered both on a register maintained by the launching state as defined in the Registration Convention (art. I) and on one maintained by the United Nations. Both registers are important.

In the Registration Convention the term “launching state” means (1) a state that launches, or (2) procures the launching of a space object, or (3) a state from whose territory, or (4) from whose facility a space object is launched (art. I (a)). The launching state may therefore be connected with a launch in one or more of four ways. A “space object” includes its component parts, and the launch vehicle and its parts, which means that debris comes within the terms of the convention (art. I (b)). The “state of registry” is a launching state on whose registry a space object is carried in accordance with the convention (art. I (c)).

Launching states maintain their own register of the objects that they have launched into Earth orbit or beyond (art. II.1). The actual content of a domestic space registry and the conditions under which it is kept up to date is a matter for each state (art. II.3). Where two or more launching states are involved with the space object they are to agree which is to enter the object on its register (art. II.2). That could be important in the operation of ARRA. By OST Article VIII the state on whose registry an object launched into outer space is carried “retains jurisdiction and control over such object, and over any personnel thereof, while in outer space or celestial body.” However, Article II.2 of the Registration Convention acknowledges that other agreements may be concluded between launching states as to jurisdiction and control over a space object and over any personnel thereof. The arrangements for the International Space Station are an obvious example.

Acting on behalf of the UN secretary-general, UNOOSA maintains a separate international register of space objects, which is publicly available online. This register has specific data requirements (art. III.1 and 2). States of registry must as soon as practicable send to the international register particular data as to any space object that they have registered (art. IV.1). The basic information required comprises (a) the name of the launching state or states; (b) an appropriate designator of the space object or its registration number; (c) the date and territory or location of the launch; (d) the basic orbital parameters, including the nodal period, the inclination, apogee, and perigee, together with the general function of the space object. A notifying state may also provide such additional information as it sees fit (art. IV.2). If the object is marked with a designator or registration number or both, that datum should be included when submitting the Article IV.1 basic information (art. V). Finally, a state should notify the UN secretary-general “to the greatest extent feasible and as soon as practicable” of registered space objects that are no longer in Earth orbit (art. VI.3). The original requirements of the convention are now supplemented by the UNOOSA Registration Information Submission Form, operational under UNGA Res. 62/101 since 2007 (UNOOSA, 2020a), and the UNOOSA/ITU Registration Guidance (UNOOSA, 2015).

The Registration Convention serves many functions. Through the UN register states or commercial entities intending a launch are able to know of satellites already in orbit provided that states have duly notified UNOOSA in good time of their launch. States can plan which orbits they themselves are to use or to license to their nationals. Registration provides the nexus between an object, its personnel if any, and a particular state for the purposes of jurisdiction in terms of OST Article VIII and for the operation of ARRA. These are matters of potential importance as satellites and space objects are now increasingly transferred on-orbit between commercial owners. Finally, it allows the identification of objects that have caused damage and which may raise questions under the Liability Convention.

Moon Agreement, 1979

The fifth space treaty is the Moon Agreement (MA) of 1979, which came into force on July 11, 1984 (CoCoSL II, 2013, pp. 325–426). Though there is much that is good in it, it has not been well accepted. By January 2020 it had 18 parties, another four states having signed but not yet ratified it. Of its parties currently only Australia, and of its signatories only France and India, might be thought of as space competent. Its purpose is to supplement the OST provisions that had included “the Moon and other celestial bodies” in its Articles I–IV and IX–XIII, with Article XI providing for all “stations, installations, equipment and space vehicles on the Moon and other celestial bodies” to be open to others “on a basis of reciprocity” following reasonable notice, maximum safety precautions, and noninterference with the normal operations of the facility to be visited.

In the main, the MA develops a legal regime for the Moon and all other celestial bodies, including the relevant trajectories and orbits used for the purpose (art. 1). In the agreement the term “Moon” includes “other celestial bodies within the solar system” other than the Earth, “except in so far as specific legal norms enter into force with respect to any of these celestial bodies” (Moon Agreement, 1979, art.1.1). International law applies (art. 2). The Moon and the other bodies are to be used exclusively for peaceful purposes (art. 3). Parties are to cooperate, the United Nations is to be informed of activities and results, scientific investigation is open to all though it is not to disturb the environment, bases may be established, and astronauts aided as required (arts. 5–10). But the MA has provisions that have proved problematic. Paragraph 5 of the preamble speaks of “benefits.” Repeating language of the OST, exploration and use of the Moon and celestial bodies is to be “the province of all mankind” and “carried out for the benefit and in the interests of all countries, irrespective of their degree of scientific or economic development” (art. 4). The resources of the moon and asteroids are declared to be “the common heritage of mankind” (art. 11.1). They are not open to national appropriation (art.11.2), and while in place they cannot become property (art. 11.3). State parties can explore and use without discrimination (art. 11.4). But when exploitation of resources “is about to become feasible” the parties are to establish an international regime to see to their “orderly and safe development,” their “rational management,” the expansion of their use, and the equitable sharing by parties of all benefits, in which distribution developing countries are to be given special consideration (art. 11.5–7). In brief, those latter provisions are why the MA has not been widely accepted. With few ratifications, and given the recent moves toward space mining and plans for manned return to the Moon, its future is uncertain.

Apart from the five UN space law treaties, other treaties have relevance for space law. Since these are mainly the outcome of the UN Conference on Disarmament and have mainly to do with stationing nuclear weapons in outer space, these are largely omitted from this article, as are the many UN General Assembly resolutions on the matter. The military use of space is an issue of increasing concern (see section “Military Use of Outer Space”).

Future Treaties?

It is unlikely that further general space law treaties will be adopted in the near future. It would be undesirable to reopen agreements on the fundamentals. Negotiation of a new general treaty would allow contentious matters to be aired, including the exact meaning of space being used for the “benefit of all.” As the relative failure of the MA shows, the major space powers are disinclined to undertake detailed legal obligations as to the distribution of “benefits” to states that are not contributing to their procurement. There is also an unwillingness of powerful states already space active to accept the curbs on their ambitions that less space-competent states might wish to see.

Principles, Resolutions, and Declarations

A number of declarations of principle and other resolutions on space have been developed within COPUOS, and all but one of these has been adopted without vote in the UN General Assembly. They provide guidance for states, as well as the persons and entities that they license, as to how space activities should be conducted. In addition, some other Assembly resolutions have relevance for space law.

Compliance with the UN Declarations and Resolutions varies. Some are fairly prescriptive, while others are hortatory or advisory. They provide formal statements that have been influential on how space activities have progressed, and it is clear that states complying with them are unlikely to be challenged. Their background, content and to some extent compliance with them is to be found in CoCoSL down to its date. Chronologically they are the following.

The immediate progenitor of the 1967 OST was the “Declaration of Legal Principles Governing the Activities of States in the Exploration and Use of Outer Space” of 1963 (UNGA Res. 1803, 1962 (XVIII)), though other UN resolutions were also important in its development (CoCoSL I, 2009, pp. 19–24).

The resolution “Principles Governing the Use by States of Artificial Earth Satellites for International Direct Television Broadcasting,” of 1982 (UNGA Res. 37/92) (CoCoSL III, 2015, pp. 1–79), so far stands alone as a space-relevant UN resolution adopted by majority vote. At the time the developing countries, a new majority within the United Nations, sought to exercise the voting power that they represented. Because the draft resolution was not supported by consensus, it could not be presented to the Assembly as the recommendation of COPUOS. It was therefore introduced by only four of its supporters and was adopted by the Assembly by a vote of 107, with 13 abstentions, 13 voting against and 24 not voting. Although it has useful points on consultations as to radio-frequency spillover and other practical matters, no state then conducting or licensing direct TV broadcasts from space, or likely to be able to do so, voted in favor. Its background were the many calls, including from UNESCO, for a New World Information and Communication Order, which would have allowed states to control media content entering and leaving them. Some of the terms of the resolution would have permitted states to bar programming of which they disapproved. Commercial pressures have proved more important tools in the control of content.

The “Principles Relating to the Remote Sensing of the Earth from Outer Space,” 1986 (UNGA Res. 41/65) calls for those conducting remote sensing to share with the sensed states the information so obtained on reasonable cost terms and asks sensing states to share and foster remote-sensing technologies in them (CoCoSL III, 2015, pp. 81–188).

The “Principles Relevant to the Use of Nuclear Power Sources in Outer Space,” 1992 (UNGA Res. 47/68) (CoCoSL III, 2015, pp. 189–266), were negotiated subsequent to the 1978 Cosmos 954 incident (Cosmos 954, 1979). They cover such matters as the criteria for the safe use of nuclear reactors and radio-isotropic batteries in satellites; safety assessment; notification of re-entry; consultations; and interstate assistance, responsibility, and liability. They should now be read along with the “Safety Framework for Nuclear Power Source Applications in Outer Space,” developed by COPUOS in cooperation with the International Atomic Energy Agency (IAEA, and welcomed by the UN General Assembly in 2009 (UNGA Res. 64/86) (CoCoSL III, 2015, pp. 167–297).

The “Declaration on International Cooperation in the Exploration and Use of Outer Space for the Benefit and in the Interest of All States, Taking into Particular Account the Needs of Developing Countries” of 1996 (UNGA Res. 51/122) (often known as the “Space Benefit Declaration”) affirms the importance of cooperation and the exchange of expertise and technologies (CoCoSL III, 2015, pp. 299–357). It has influenced subsequent space activities.

Similarly, “The Space Millennium: Vienna Declaration on Space and Human Development,” adopted in 1996 as part of the “Third UN Conference on the Exploration and Peaceful Uses of Outer Space” (UNISPACE III) expresses hope for international cooperation and collaboration and the extension of the benefits of space to all (CoCoSL III, 2015, pp. 358–362).

The resolution “Application of the Concept of the Launching State” of 2004 attempts to clarify the use of “launching state” as a term of art, which is crucial for ARRA, and the Liability and Registration Conventions (UNGA Res. 59/115) (CoCoSL III, 2015, pp. 363–400). In particular, paragraph 3 recommends that COPUOS invite states on a voluntary basis to keep it informed as to in-orbit transfers of satellite ownership.

The title of the “Recommendations on Enhancing the Practice of States and Other Intergovernmental Organizations in Registering Space Objects” of 2006 indicates its content (UNGA Res. 62/101) (CoCoSL III, 2015, pp. 401–481). Registration practice should be harmonized. This has to some extent happened, aided by UNOOSA producing its own Registration Information Submission Form (UNOOSA, 2020a); CoCoSL III, 2015, pp. 476–481 on the 2008 version) and a document on registration guidance (UNOOSA, 2015).

In 2007 the Assembly endorsed the “Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space,” calling for efforts to combat space debris (UNGA Res. 62/217, paras. 26–28) (CoCoSL III, pp. 605–657). It is noticeable that increasingly national state licensing of space activities includes conditions as to the lessening and avoidance of the creation of debris (UNOOSA, 2015).

The “Recommendation on National Legislation Relevant to the Peaceful Exploration and Use of Outer Space” of 2013, sets out how a state involved in space activities should frame an appropriate regulatory framework, including compliance with the space treaties (UNGA Res. 68/74) (CoCoSL III, 2015, pp. 483–603).

In 2019 COPUOS adopted “Guidelines for the Long-term Sustainability of Outer Space,” which may be considered by the UN General Assembly in 2021 (Guidelines, 2020). These provide for continuous monitoring of space activities and call for voluntary compliance with generally accepted norms.

In 2020 the UN General Assembly adopted several space-related resolutions. These include on “Prevention of an Arms Race in Outer Space” (UNGA Res. 75/35), on the “Reducing Space Threats Through Norms, Rules and Principles of Responsible Behaviours” (UNGA Res. 75/36) and on “No First Placement of Weapons in Outer Space” (UNGA Res. 75/37). It remains to be seen what practical effect these will have in space law.

The Artemis Accords of 2020 is not a UN resolution, but it is a statement of principles agreed between its parties. They were brokered by the United States concomitant with the NASA Artemis program for a return to the Moon (Artemis Accords, 2020). Their principles for cooperation rehearse those already contained in the UN treaties, though there is no reference to the Moon Agreement. They include the preservation of significant landing sites and equipment (sec. 9), that extraction and use of space resources for the benefit of humankind should be safe and sustainable (sec. 10), that due regard be given to the activities of others and that there should be no intentional interference with the activities of others including how interference can be avoided (sec. 11), and that space debris should be mitigated including by de-orbital strategies (sec. 12). Party to the Accords so far are Australia, Brazil, Canada, Italy, Japan, Luxembourg, the United Arab Emirates, the United Kingdom, the Ukraine, and the United States.

Cooperative Associations

Much of the requirements of space law is implemented through formal and semi-formal cooperative associations of those conducting space activities. There are a large number of agreements among small groups of states, governmental and nongovernmental organizations, space agencies, and space-active entities. Examples range from the agreements and memoranda of understanding behind the International Space Station and similar efforts (Lyall & Larsen, 2018, pp. 337–358), to the Inter-agency Debris Coordination Committee and the International Asteroid Warning Network.

The Boundary Question

Any system of law applies only within the limits of its “jurisdiction”—where it applies: jus = law; dico, dicere = to say. That may be within the territorial confines of a state or may be wherever states have agreed that it applies. As noted, some space law is terrestrial, but what about “space” itself? Where is that? While a substantial body of air law existed before space activities became feasible, where space “is” as a location is not defined in or by international law. Recently, in the domestic legislation under which they license space activities, some states have adopted delimitation rules based on altitude, but the fact remains that as a matter of general international law “space” remains undefined. Everyone knows it is “up there,” but where it “begins” remains legally unknown (UNOOSA, 2020b). The application of the MA is limited to the Moon and other celestial bodies within the solar system, excluding the Earth (Moon Agreement, 1979, art. I.1).

No state has formally objected to a satellite passing over its territory. Seven equatorial countries have claimed jurisdiction in respect to the portions of the geostationary orbit above their territories, but this has not been accepted by other states and been without practical effect (Bogota, 1976; Meija-Kaiser, 2020, pp. 80–109).

Orbits and Debris

Orbits are limited natural resources to be used “rationally economically and efficiently” (ITU CS, 2020, art. 44.2). However, orbits are available on a first come, first served basis. The monitoring of space objects and space situational awareness programs in a number of countries and arrangements for the interchange of information between them are of increasing importance (Lal et al., 2018; ESPI, 2021). It remains the case, however, that valuable orbits could become unusable if clogged by defunct satellites and space junk.

When a state licenses the launch of a satellite the orbital data as to nodal period, inclination, apogee, and perigee are included in the data to be registered both in its national register and in that maintained by UNOOSA on behalf of the UN secretary-general (Registration Convention, 1976, art. IV; cf. UNOOSA, 2015; UNOOSA, 2020a). It is now normal in appropriate cases for a license to provide for the de-orbiting of the satellite at the end of its useful life (e.g., Artemis Accords, sec. 12) or for the satellite to be relocated to a “graveyard orbit” in the cases of satellites in geostationary orbit or those having a nuclear battery (ITU, 2010; Meija-Kaiser, 2020, pp. 197–274). De-orbiting into the atmosphere runs the danger of an incomplete aerial destruction (Liability Convention, 1972; Cosmos 954, 1981).

Major problems are likely to occur through the proliferation of constellations or swarms of cube-sats and the like, orbited for many purposes. The International Astronomical Union (2021) and others have expressed reservations about the interference of these constellations with optical astronomy. At low orbits such satellites may have a very short life, but their densities, orbits, and requirements for radio spectrum resources will be difficult to deal with. Constellations may also cause difficulties for launches into orbits beyond low Earth orbit. At higher orbits satellite lifetimes will be longer, but de-orbiting and replacement launches will complicate matters (Froehlich, 2019; Marboe 2016; Stubbe, 2017). Space situational awareness (an inelegant phrase) remains an area of difficulty.

At the start of the space age little attention was given to the problem of orbital debris. Now it is clamant (ESA, 2021), and there is the danger of a cascade effect as satellites and debris collide producing chaos (Kessler & Cour-Palais, 1978). Avoiding creating debris and mitigating the amount of debris to least possible levels is called for in the COPUOS “Space Debris Mitigation Guidelines” of 2007 (see section “Principles, Resolutions, and Declarations”), the UNOOSA guidelines as to registration practice (UNOOSA, 2020a), and is promised in Section 12 of the Artemis Accords. The Inter-agency Debris Coordination Committee (IADC) has produced guidelines and a manual on the matter (CoCoSL III, 2015, pp. 605–652). Other bodies such as NASA and the European Space Agency operate their own guidelines.

There is no unified program for the removal of spent satellites, debris and other space junk, but such bodies as NASA and ESA are investigating the possibilities (Froehlich, 2018; Stubbe, 2017).

Near-Earth Objects

The Chelyabinsk and Tunguska events, together with the possible link between the Chicxulub Crater and the disappearance of the dinosaurs, have increased interest in, not to say fear of, near-earth objects. Monitoring near-earth objects has increased, such as NASA and ESA having their own programs. UNOOSA now acts as the secretariat for the meetings of the International Asteroid Warning Network and of the Space Mission Planning Advisory Group, voluntary associations of observatories and other space institutions, which are otherwise linked with COPUOS. A series of planetary defense conferences has been arranged by the International Academy of Astronautics. Methods for deflecting or destroying major threats are often reviewed in the scientific literature. Probably using a nuclear explosion for the purpose would be thought to be a reasonable exception to the ban on nuclear weapons in space (Koplow, 2019). However, as yet no formal structure through which such could be agreed or accomplished has been established. This remains an area of informal active discussion within the general purview of space law.

Exploration and Use

States are responsible for their activities in outer space, including the activities of their nationals, a responsibility that is normally implemented for nationals through a licensing system (OST art. VI). The exploration and use of outer space are free and are to be carried out for the benefit and in the interests of all countries without discrimination (OST art. I). Cooperation and mutual assistance, with due regard for the interests of other states, is called for. Harmful contamination of celestial bodies or adverse effects on the Earth from the introduction of space materials are to be avoided (OST art. IX). “Space Mining” is discussed later in this article.

Scientific investigation may be engaged in freely (OST art. I). To encourage cooperation states are to inform the UN secretary-general, the public, and the international scientific community of the nature, conduct, locations, and the results (OST art. XI). However, the obligation to inform extends only to “the greatest extent feasible and practicable,” a limitation capable of individual interpretation by each space-active state.

The Moon and other celestial bodies are to be used exclusively for peaceful purposes. Nuclear weapons are forbidden, as are military bases and installations, though military personnel may engage in scientific research (OST, art. VI; Moon Agreement, art. 3).

States may inspect the installations, facilities, and equipment of other states on celestial bodies. Due notice must be given of visits for the purpose. There must be the maximum precautions to assure safety, and interference with the normal operations of the facilities must be avoided (OST art. XII; 2001).

There have been suggestions that lunar landing sites and artifacts left there should have a protected legal status (Westwood et al., 2017). Section 9 of the Artemis Accords speaks of preserving space heritage, including such items, and the United States has legislated requiring due regard be given to space heritage in its activities (United States, 2020). MA Article 7.3 contemplates special protective arrangements for international scientific preserves, a concept that may be extended. Perhaps UNESCO will redefine the world heritage that it recognizes.


A potential harmful interference of a proposed space activity with the activities of other states requires consultation with them (OST art. IX), but, with the exception of radio interference (see section “Radio”), what a harming interference may be remains obscure. Suffice it to say that bodies such as the Interagency Operations Advisory Group, the Space Frequency Coordination Group, and others, many serviced by UNOOSA, play useful roles in avoiding or mitigating interference between space activities. Agreements brokered by such groups, and their recommendations, do not have formal legal force but are extremely important in the use of space.

Space Tourism

The possibility of “space tourism” services has emerged recently. A swift “up and down” trip will be governed by national laws and will probably additionally come under normal international legislation if the landing is elsewhere than the country of origin. Space tourism will certainly require strict training standards for crew as will clarity as to the authority of the commander of the flight. The “informed consent” and health certification of all participants will be necessary. Whether tourist passengers are “astronauts” for all purposes of space law remains uncertain despite the language of some advertising. They might well be subject to separate conditions in insurance law. The Agreement on Rescue and Return Convention refers merely to the personnel of a spacecraft without differentiation (ARRA, arts. 2 and 4). But, does a non-orbital flight bring its participants into the category of astronaut and therefore of the “envoys of all mankind” to be assisted as required? (OST art. V). It is hard to believe they would be excluded from ARRA, but some interpretive flexibility may be called for.

Space Mining

Space mining is likely to become contentious both in law and in actual commercial activity.

The prohibition in OST Article II of national appropriation “by claim of sovereignty, by means of use or occupation, or by any other means” excludes sovereign appropriation by states or by private individuals and entities. Any individual may make a claim, and some will offer to sell a plot on the Moon based on their asserted title, but as a matter of law this is ineffective. Any “title,” valid against third parties, depends on it being accepted by a national legal system. That said it is open to states to recognize as valid claims of ownership of materials procured in space from natural objects, and samples from the Moon and asteroids have been treated as “property” when brought to Earth. Section 402(a) of Title IV of the U.S. Commercial Space Launch and Competitiveness Act, 2015, on “Space Resource Exploration and Utilization” extends that classification to materials mined from celestial bodies in space (United States, 2015). So does the Luxembourg Law on the Exploration and Use of the Natural Resources of Space of 2017 (Luxembourg, 2017); it being crafted to encourage entrepreneurs to create Luxembourg companies to engage in such activities. A 2019 United Arab Emirates law on the regulation of its space sector also provides for space mining. Such may, or may not, be lawful under the MA, but the United States, Luxembourg, and the United Arab Emirates have not signed that treaty, let alone ratified it. It is notable that Section 11 of the Artemis Accords of 2020, which all three have signed, contains provisions about having due regard to the activities of others and how conflict in exploitative activities might be avoided, including through the use of safety zones. Needless to say, academic discussion is under way (Bittencourt Neto et al., 2020).

Remote Sensing

Remotely sensed data may be obtained by surveillance from aircraft and from satellites in space (Brünner et al., 2019). Remote sensing is available for many purposes, and sensing from space is in accordance with the “benefit of all” principles of OST Article I, permitting better weather forecasting, monitoring environmental and climate change, geological mapping, and even archaeology. The dissemination of its scientific results is required by OST Articles I and VI. While commercial companies now provide most remote-sensing services, some sensing is done for their purposes by international organizations such as the World Meteorological Organization and ESA, which make their data available to researchers. Other aspects of space law are also relevant. Thus the launch and operation of the satellites have to be licensed by states and must comply with the normal requirements for such matters, as outlined elsewhere. Radio links, whether terrestrial or satellite, must be properly assigned and registered (see section “Radio”) and, in the case of satellites, orbits planned.

When COPUOS was discussing what became the 1986 “Principles on Remote Sensing” (UNGA Res. 41/65) some states wanted any sensing to be made contingent on the permission of the sensed state and for it to have control of the data thereby obtained. The principles do not require that permission but do call for respect for the sovereignty of sensed states, for the sensing not to be detrimental to their interests, and for them to have access to the information obtained. The principles are silent as to national security, though some might interpret “detriment” as including that as well as other elements. Cooperation, participation, and technical assistance are all called for, albeit on “equitable and mutually acceptable terms” whatever that in practice may mean (Ito, 2011).

Global Positioning

Global-positioning satellites provide accurate and continuing location services for many purposes, including aviation, marine navigation, monitoring tectonic plate movement, and even predicting volcanic activity. The satellite signals are also used for the exact time stamping of international currency transactions and other events.

The various global navigation positioning systems (GNSS), the U.S. Global Positioning Service (GPS), the European Galileo service, the Russian Glonass and the Chinese Beidou systems, and the regional systems for India (IRNSS and NavIC) and Japan (QZSS) are compliant with the “benefit of all” requirements of OST Article 1 (Lyall & Larsen, 2018, pp. 337–358). However, their operators may restrict access to their services. Thus the U.S. GPS system is occasionally unavailable when U.S. military forces are engaged in training activities. Both it and the European Galileo system have a higher accuracy positioning potential that is available only to selected (paying?) users. Augmentation assistance, such as the European EGNOS system for Galileo, and the Wide Area Augmentation Service (WAAS) for North America, is available to increase positional accuracy through terrestrial beaconing.

GNSS systems are all state operated or closely supervised. The commercial Inmarsat and Iridium communications systems provide links for the Global Maritime Distress and Safety System (GMDSS) of the International Maritime Organization and are supervised by the International Maritime Satellite Organization to secure their public service obligations in respect of the system.

International coordination and interoperability of GNSS systems is arranged through the International Civil Aviation Organization (ICAO), the International Maritime Organization (IMO), the International Telecommunication Union (ITU), a COPUOS International Committee on GNSS (ICG), and by bilateral arrangements between the United States, the European Union, Russia, China, India, and Japan.

Military Use of Outer Space

Much of how outer space is used for military purposes and how it is organized is unknown. Military radio installations are not subject to the ITU radio regulations, although they are expected to provide assistance in cases of distress, prevent harmful interference, and to comply with the administrative regulations when providing public communication services (ITU CS art. 48). Otherwise it is obvious that military forces use remote sensing, global positioning, and radio communication by satellite. Military bases and installations in space or on celestial bodies are forbidden, though military personnel may engage in scientific research (OST, art. VI; Moon Agreement, art. 3). Stationing nuclear weapons or weapons of mass destruction in space is also prohibited (OST, art. IV). Nuclear explosions in space are unlawful, though few would object to using nuclear weapons to destroy or deflect an incoming asteroid (NTBT, 1963–1964; Koplow, 2019).


Many planetary science investigations require radio communication, and it may be fairly said that modern society is heavily dependent on radio services. Nationally the use of radio is regulated by states. However, any transmissions that cross national boundaries should comply with interstate agreement reached through the ITU. Communications to and from satellites in orbit obviously fall within that category though any transmission may do so depending on the power with which it is made. Importantly, the negotiations and the legislation as to what the rules should be are constrained by the laws of physics. Those laws cannot be modified or repealed by human diktat. If no accommodation is arrived at, one use of the radio spectrum will interfere with another, and all will lose. Through the ITU, therefore, states arrive at mutually acceptable decisions, solutions, and compromises (Lyall, 2011; Lyall & Larsen, 2018, pp. 189–225).

The International Telecommunication Union—The ITU

The ITU is the oldest major active international organization (Codding, 1952; Lyall, 2011). Like the United Nations the ITU has 193 state members, all but one also being UN members. In addition, the ITU has more than 800 associate members (Lyall, 2011).

The historical roots of the ITU are twofold. First wired communications were dealt with through an international body, the International Telegraph Union established in 1865, replacing a number of bilateral and small multilateral treaties (Paris, 1865). Second, principles for the use of radio signals that crossed international boundaries were initially set out in 1906 (Berlin, 1906). These were that particular frequencies should be used for specific named services, that the minimum transmission power necessary for the intended communication should be used, and that the best available equipment should be employed to confine the spread of the transmission across frequency bands. However, no formal radio union was ever created to deal with wireless communication.

Over the years the international regimes for both “wired” and “wireless” services were revised and were brought together in 1932 to form the ITU (Madrid, 1932). In 1947, and after some necessary structural adaption, the ITU became one of the UN’s specialized agencies (Atlantic City, 1947). The ITU persisted in its 1947 form until 1996 when a major restructuring took effect (Geneva/Kyoto, 1992, 1994). The ruling documents are now a constitution (CS), a convention (CV), and two sets of administrative regulations, each having status as an international treaty. All four treaties bind all ITU members (ITU, 2020). In the new structure major operational responsibilities were entrusted to three sectors. There has been no major change since the new system came into force in 1996, and no tweaks to it since 2010. Overall the reorganization has been a success.

Operationally, the ITU consists of a plenipotentiary conference, a council, three sectors permanently based in Geneva, each with a director and a bureau, and a general secretariat (CS arts. 7 and 11).

The plenipotentiary conference of all the state members meets every 4 years usually for 2–3 weeks. It determines general policies, plans, deals with reports from the council, and sets ITU budgets. It also, with “due regard to the need for equitable distribution” elects the council, the secretary general, the deputy secretary general, and the directors of the sectors, all of whom must be of different nationalities, and the members of the Radio Regulations Board.

Membership of the council consists of not more than 25% of ITU state membership, and as of 2021 stands at 48. Meeting annually, it acts on behalf of the plenipotentiary conference between its conferences. The council is the governing body of the union, overseeing compliance with the CS, the CV, and the administrative regulations. It implements the decisions of plenipotentiary and other conferences, supervises the management of the union, approves staff and financial regulations, and takes any action necessary for the functioning of the ITU.

The ITU Sectors

Each of the sectors, ITU–D, ITU–T and ITU–R, has a director and operates through a bureau. Any state member may join a sector. Associate sector members are entities other than states and range from manufacturers and telecommunications operators to academic and scientific institutions. They are permitted to join sectors or the working parties that deal with questions within the remit of the sector. Sectors can and do interrelate and cooperate as necessary.

The Development Sector (ITU–D) was an innovation of the 1990s reconstruction. As its name suggests, through working groups, conferences, and other activities, it fosters developments in telecommunications, the exchange of information and expertise, and has particular regard to those states requiring assistance. However, it does not adopt binding rules.

The Standardization Sector (ITU–T) is responsible for setting standards for communications equipment and their operation. Normally, World Standardization Assemblies are convened every 4 years. Between assemblies, ITU–T operates through working groups. Standards adopted by its assemblies are legal rulings; however, two points should be noted. First, to circumvent delay an “alternative approval” system has been adopted that allows a reaction to developments in technology swifter than that of the 4-year cycle. Alternative approvals are not legally binding, but the system usually works satisfactorily. Second, ITU–T is not the only body setting standards for communications equipment and their use; other national and regional standardization bodies exist.

The International Telecommunication Regulations, the ITRs, one element of the ITU administrative regulations, fall within the responsibilities of ITU–T. The ITRs deal the working of the international telecommunication system and with the settlement of accounts generated in the operation of international telecommunication services. Regrettably, because of disagreement, two sets of ITRs exist, 1988 (Melbourne, 1989) and 2012 (Dubai, 2013), the latter arguably permitting states to monitor and control the content of internet communications (Hill, 2014; Lyall, 2011, pp. 175–178).

The Radiocommunication Sector (ITU–R) is important in the development and application of the Radio Regulations (2019), the other element of the ITU administrative regulations. It maintains the crucial Master International Frequency Register (MIFR).

The radio spectrum and any associated orbits are limited natural resources to be used “rationally, efficiently and economically” in accordance with the Radio Regulations (RR) (CS art. 44.2). Military radio stations are not subject to the RR but are expected normally to conform to them as to interference, emission levels, and frequency use, particularly when broadcasting nonmilitary programs (CS art. 48).

The RR are agreed at four-yearly World Radiocommunication Conferences (WRCs), each conference usually dealing with only a portion of the radio spectrum and, on occasion, only with a particular global area.

RR Article 4 deals with the assignment and use of frequencies. Its provisions include that states limit their use of spectrum and bandwidth to the minimum necessary for services (RR art. 4.1). States are to conform to RR Article 5 when assigning frequencies to stations capable of causing harmful interference to the services rendered by other states (RR art. 4.2).

RR Article 5 contains the Table of Allocations in which frequency bands are set aside for particular uses. For its purposes the world is divided into three regions, roughly Europe including Russia and Africa (Region 1), the Americas (Region 2), and the rest of the world (Region 3) (RR art. 5.1–5). In addition, account may be taken of the special radio conditions found in an African Broadcasting Area (RR art. 5.10–13), a European Broadcasting Area (RR art. 5.14–15) and a Tropical Zone (RR art. 5.16–22).

For planetary science three elements of the RR are important: the allocations of radio frequencies for terrestrial links, those for communication to and from satellites, and the “quiet” portions of the radio frequencies that are protected for radio astronomy and similar activities.

RR Article 5 allocates frequency bands for specific purposes and services in each of the three RR regions, often with precautions against their use being subjected to interference. States license radio stations, whether transmitting or receiving, to operate on frequencies assigned in accordance with RR Article 5 allocations and notify the assignment to the ITU–R bureau for inclusion in the MIFR. Usually states send in a preliminary notification to alert others as to their intentions, thus allowing negotiation of any coordination with assignments by other states that may be needed. In deciding on an assignment a state can be assisted through the ITU–R sponsored Space Frequency Coordination Group, which meets annually. The 2015 UNOOSA/ITU guidance on registration procedures provides useful insights (UNOOSA, 2015, pp. 11–18).

Particular provision is made for some satellite services. RR Appendix 30 and its annexes provides for all services and associated plans for the broadcasting satellite services in particular frequency bands in Regions 1, 2, and 3. RR Appendix 30A and its annexes does the same for feeder links for broadcasting services. RR Appendix 30B and its annexes provide for the fixed-satellite service in particular frequency bands and associated plans.

The Master International Frequency Register (MIFR) is a listing of all the assignments made by states to the radio stations they have licensed that conform to the requirements of the RR. The general position is that when an assignment is notified to the Radiocommunication Bureau it is examined to see it conforms to RR requirements and that it will not cause harmful interference to assignments already entered on the MIFR. If harmful interference is likely, the notification is referred back for consultation with the other affected states so that, if possible, an accommodation can be arrived at. If so, the revised assignment will be registered. Not all cases of interference bar registration in the MIFR.

Under RR Article 1 interference is defined as “the effect of unwanted energy due to one or a combination of emissions, radiation, or inductions upon reception in a radiocommunication system, manifested by any performance degradation, misinterpretation, or loss of information which could be extracted in the absence of such unwanted energy” (RR art. 1.166). Permissible interference is defined as “observed or predicted interference which complies with quantitative interference and sharing criteria contained in the Regulations or in ITU-R Recommendations or in special agreements as provided for in these Regulations” (RR art 1.167). Accepted interference is “interference at a higher level than that defined as permissible interference and which has been agreed between two or more administrations without prejudice to other administrations” (RR art. 1.168). Harmful interference is “interference which endangers the functioning of a radionavigation service or other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with Radio Regulations” (RR art. 1.169).

In the case of space related activities the scrutiny of a notified transmission assignment is carried out by a specialized division within the ITU–R bureau, the Space Services Department (SSD, 2021). Of potential importance for planetary scientists, particularly for those reliant on space probes, the SSD operates a Satellite Interference Reporting and Resolution System (SIRRS, 2021) through which difficulties can be identified and resolved.

Radio Astronomy

RR Article 5 identifies a number of “quiet” portions of the radio spectrum in which radio signals are barred to protect radio astronomy and similar “listening” activities such as the Search for Extra-Terrestrial Intelligence. States should not authorize transmissions within these bands. However, it is up to individual states whether they wish to demarcate radio quiet zones within their territories for such purposes. An interesting development is that RR Article 22.22–25 prohibits radio emissions causing harmful interference in a defined “shielded zone” that is on the other side of the Moon and hence protected from much Earth-originating interference. It is unclear how such matters will develop as the exploitation of the Moon proceeds and a Moon-based telecommunication system is needed.

The Search for Extra-Terrestrial Intelligence (SETI)

Apart from the protective “listening” or “silent” provisions in the RR just outlined, there is no interstate agreement on the Search for Extra-Terrestrial Intelligence. There is, however, a SETI Permanent Committee within the International Academy of Astronautics, which in 2010 published a draft “Declaration of Principles Concerning the Conduct of the Search for Extraterrestrial Intelligence.” This consolidates a 1989 declaration on how a potential or actual detection should be handled and a 1995 draft on how a “reply communication” should be authorized and its content determined. Overall cooperation between searchers is called for, particularly as to verification of results, together with the involvement of the scientific community and the United Nations in any follow-up. Publicity through the media should not be premature (Lyall & Larsen, 2018, pp. 483–507).

Dispute Settlement

Many disputes arising from space activities are dealt with through national legal systems and may involve private international law, which is an area separate from the material of this article. International disputes are usually settled by mediation, conciliation, negotiation, and compromise. If that fails, a dispute may be subject to arbitration or other procedures agreed to in the instrument or contractual provision from which it arises. Thus the European Space Agency constitution provides that internal disputes are dealt with by arbitration, as does the ITU constitution. In 2011 by adopting Optional Rules for the Arbitration of Disputes Relating to Space Activities, the Permanent Court of Arbitration made its procedures available for both private and public entities including states to settle their differences as to space activities (Permanent Court of Arbitration, 2011). Occasionally, when appropriate, national civil court procedures may be invoked. Finally, in the ultimate the International Court of Justice could be asked to decide an inter-state space law dispute.


Space law continues to evolve and develop. New uses of space technologies and, increasingly, their commercial exploitation, present intriguing legal problems for solution by its practitioners. But the basic principles agreed to and set out in the 1960s remain its foundation.


ITU Constitution—see ITU, 2020.
Consolidated Treaty Series. New York: Oceana, 1969–1991.
ITU Convention—see ITU, 2020.
The ITU Development Sector.
The ITU Radiocommunication Sector.
The ITU Standardization Sector.

Telecommunication treaties and other materials are available through the ITU main website and the ITU History Portal.

Further Reading

  • Brierly, J. L. (1938). The law of nations: An introduction to the law of peace. Oxford University Press. (Reprinted in 1955 and 1963)
  • Chapman, A. (2012). Brierly’s law of nations: An introduction to the role of international law in international relations (7th ed.). Oxford University Press.
  • Cheng, B. (1997). Studies in international space law. Clarendon Press.
  • Christol, C. Q. (1982). The modern international law of outer space. Pergamon Press.
  • Dunk, F., & Tronchetti, F. (Eds.) (2015). Handbook of space law. Edward Elgar.
  • Gaeta, P., Viñuales, J. E., & Zappalà, S. (2020). Cassese’s international law (3rd ed.). Oxford University Press.
  • Hobe, S. (2019). Space law: A handbook. Beck.
  • Jakhu, R. S., & Dempsey, P. S. (2017). Routledge handbook of space law. Routledge.
  • Jakhu, R. S., & Pelton, J. N. (Eds.). (2017). Global space governance: An international study. Springer International.
  • Jenks, C. W. (1965). Space law. Praeger.
  • Lachs, M. (2010). The law of outer space: An experience in contemporary law-making. Nijhoff. (Original work published 1972)
  • Leive, D. M. (1970). International telecommunications and international law: The regulation of the radio spectrum. Oceana.
  • Levin, H. G. (1971). The invisible resource: Use and regulation of the radio spectrum. Johns Hopkins University Press.
  • Lowe, V. (2015). International law: A very short introduction. Oxford University Press.
  • Masson-Zwaan, T., & Hofmann, M. (2019). Introduction to space law. Kluwer.
  • McDougal, M., Lasswell, H. D., & Vlasic, I. A. (1963). Law and public order in space. Yale University Press.
  • Smulyan, S. (1994). Selling radio: The commercialization of American broadcasting, 1920–1934. Smithsonian.
  • United Nations Office for Outer Space Affairs. (2019). Annual Report 2019.
  • United Nations Office for Outer Space Affairs. (2014). Education curriculum on space law.


  • Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space (ARRA). (1968, 22 April). 672 UNTS 119; 1969 UKTS 56, Cmnd. 3997.
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  • 1. In the film 2001: A Space Odyssey, the United States declines a request by the USSR to inspect its Clavius Base on the Moon on the grounds that the facility was harboring an infection.