Panel 1 3rd speaker - How can the principle of due regard be applied to address threats arising from State behaviours with respect to outer space? - Setsuko AOKI

Oct 22, 2026

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Explores how the Outer Space Treaty’s “due regard” obligation can mitigate threats linked to State behaviours in outer space. After introducing the interpretive “due regard” test and clarifying that due regard is independent of related consultation, contamination-avoidance, and interference-related duties, the discussion examines how the term operates in other areas of international law, then derives space-specific, criteria-focused steps for applying due regard to relevant space activities and responsibilities.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages4

Reading Time10 min

AccessFree to download

1. Introduction: potentials of “due regard” test

Article IX and the independence of due regard obligations

Rationale for legal responsibility without new instruments

2. “Due regard” principle in other fields of international law

International civil aviation and law of the sea usage

UNCLOS terminology and state practice

ICJ, arbitration, ITLOS, and ICRC perspectives

3. To develop specific criteria of “due regard” in space activities

Preliminary findings and space-law considerations

9 May 2022 Panel 1 3rd speaker “How can the principle of due regard be applied to address threats arising from State behaviours with respect to outer space?” Setsuko AOKI Professor of Law, Keio University Law School, Japan 1. Introduction: potentials of “due regard” test Thank you so much for giving me the opportunity to talk on the subject of “how can the principle of due regard be applied to address threats arising from State behaviours with respect to outer space?” My name is Setsuko AOKI, professor of law, Keio University Law School, Tokyo, Japan. It is not sufficiently recognized that the Outer Space Treaty, the most important treaty in the field of international space law, has an effective principle of “due regard” to substantially mitigate threats arising from State behaviors with respect to outer space. The first sentence of Article IX provides that “States Parties to the Treaty shall be guided by the principle of cooperation and mutual assistance and shall conduct all their activities in outer space, including the Moon and other celestial bodies, with due regard to the corresponding interests of all other States Parties to the Treaty.” Article IX has other three sentences providing obligations to avoid harmful contamination in outer space and adverse changes of the Earth environment, the obligation to seek a prior international consultation when a State is likely to cause potentially harmful interference with activities of other States, and the right of a State to request consultation to the State which is likely to cause potentially harmful interference with its space activities. The obligation of due regard is independent of these three obligations and the right, and as such, the meaning and the criteria to apply due regard obligation have to be analyzed independently. Reading only the first sentence of Article IX leads to the understanding that due regard is self-restraint in space activities on the part of States Parties based on reciprocity and equality of States , and it is strengthened by the obligation of international cooperation. This interpretation is reinforced by other articles of the Outer Space Treaty that reassure the legal obligations of common interests and the freedom of space activities on a basis of equality. As “due regard” is clearly mentioned as a legal obligation in Article IX , noncompliance with due regard in a specific space activity would be the violation of the Outer Space Treaty that could lead to the pursuit of international responsibility of the State attributable to that violation. A new legally-binding instrument is not needed to pursue international responsibility. This merit should not be underestimated. However, as relatively less attention has been paid to due regard in international space law up until now, the meaning, contents or criteria to determine “due regard” is not clear enough to directly apply this test to address threats in space activities. Therefore, with the help of other fields of international law that have established “due regard” rule for allocating responsibilities between relevant States, the meaning and criteria of “due regard”obligation is presented. Then, necessary measures and steps for the effective application of“due regard” in space activities will be contemplated. 2. “Due regard” principle in other fields of international law Looking into other fields of international law, with respect to treaties, “due regard”obligation was first appeared in the 1944 Convention on International Civil Aviation , which provides that States Parties undertake that State aircraft shall have due regard for the safety of civil aviation. The term “due regard” is found about 10 times in the United Nations Law of the Sea Convention (UNCLOS) , among which the reference to high seas freedoms that shall be exercised with due regard for the interests of other States (Art. 87(2)) seems to have close resemblance to due regard obligations specified in the O

FAQs

What does Article IX’s “due regard” require for States Parties?

Article IX states that States Parties conduct their outer space activities with due regard to the corresponding interests of all other States Parties. The speaker also explains that due regard stands as a separate obligation from other Article IX duties and rights.

Why is due regard considered independent from other obligations in Article IX?

The presentation argues that due regard is independent of other obligations (such as harmful contamination avoidance and consultation duties) and of the right to request consultation. Therefore, its meaning and criteria must be analyzed on their own.

How can due regard be applied specifically to threats in outer space?

The talk proposes developing space-specific criteria by drawing on “due regard” concepts from other fields of international law, while accounting for outer space’s vulnerability and the strengthened role of international cooperation emphasized in Article IX.

Oct 22, 2026

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