Defining the Customary International Law of Outer Space

by Julian Ku

The Office of Science and Technology Policy released last week the new “National Space Policy of the United States.” According to the Washington Post, the new space policy, which supersedes a 1996 Clinton-era space policy, envisions a greater role for the military in outer space. Here are some of the new policy’s fundamental principles, a number of which seem to stake out possible international law positions.


  • The United States rejects any claims to sovereignty by any nation over outer space or celestial bodies, or any portion thereof, and rejects any limitations on the fundamental right of the United States to operate in and acquire data from space;

  • The United States considers space systems to have the rights of passage through and operations in space without interference. Consistent with this principle, the United States will view purposeful interference with its space systems as an infringement on its rights;
  • The United States considers space capabilities — including the ground and space segments and supporting links — vital to its national interests. Consistent with this policy, the United States will: preserve its rights, capabilities, and freedom of action in space; dissuade or deter others from either impeding those rights or developing capabilities intended to do so; take those actions necessary to protect its space capabilities; respond to interference; and deny, if necessary, adversaries the use of space capabilities hostile to U.S. national interests;
  • The United States will oppose the development of new legal regimes or other restrictions that seek to prohibit or limit U.S. access to or use of space. Proposed arms control agreements or restrictions must not impair the rights of the United States to conduct research, development, testing, and operations or other activities in space for U.S. national interests;

It would be an understatement to say that I’m not an expert on “space law”. The various U.S. positions here (not all of which depart from the 1996 Clinton policy) take place against the background of a space law treaty system (see here for the five key treaties or the text of those treaties can be found here).

While extensive, these treaties still leave a lot of questions open. The right of “passage through and operations in space without interference” is not found in the Outer Space Treaty and the scope of this right is unclear. Can a country try to jam or interfere with a U.S. satellite passing over that country’s territory? The U.S. may be trying to stake out a rule here, which might indeed solidify into a rule of customary international law. The U.S. President has the authority to take a position on these rules and it strikes me that this is a good example of where it make sense to give the executive unfettered authority to develop or reject new rules of CIL.

Or perhaps there is no real likelihood of CIL developing in our modern positivist treaty-laden age. Space law is truly a new area of law and is in many ways unburdened by custom. The law of outer space, such as it is, is likely to be all about treaties. But if it is going to be custom driven at all, I imagine that (uncontroversially), its rules will largely be developed unilaterally by various U.S. Presidents over the next few decades.

2 Responses

  1. Some quick thoughts about this:

    It is now commonly believed that in space law, the treaty making epoch is over. It ended somewhat late 70’s, and was followed by an epoch in which law making was done through GA declarations (e.g. remote sensing principles and nuclear power sources principles). These then could evolve into customary international law, as is the general opinion that the remote sensing principles are already customary. Now the law making is somewhat in a stand-still, and the only declarations made are interpretative ones.

    The new US policy seems to be in line with the current corpus of space law. The snippets in the post are a US kind of reiteration of Art I, II and IX of the Outer Space Treaty.[1] I don’t think this policy contains anything unusual, although it does sound a bit imperialistic to me.

    Anyway, it is my belief that in space law, it will not be the US alone to make CIL. Even for the US space is too expensive to get there alone, so it is through cooperation, and thus mutual interests, that spacefaring is done.

    [1] A somewhat technical note on right of passage: a satellite in orbit flies at 20 000 kph and more, and cannot or can hardly manoeuvre. Right now it is technically impossible to impede or interfere with the right of passage over one’s territory. Perhaps in the future.

  2. Space Law: The USA’s New Jingoistic Space Policy

    The United States issued a new National Space Policy that shrugs off the yoke of common international law and related international treaties; declares sovereignty over the entirety of outer space and celestial bodies; and promises to take action against any nation that attempts to impede its use of outer space. According to an article by the Washington Post (h/t Opinio Juris), four years earlier, a congressionally chartered panel led by Defense Secretary Donald H. Rumsfeld recommended developing space weapons to protect military and civilian satellites. However, the administration claims that there is no space arms race. This seems highly unlikely

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