Can the “due regard” obligation in Article IX of the Outer Space Treaty (OST) be interpreted as giving legal priority to first movers in space, such as those initiating mining or scientific activities on the Moon or Mars? Could early entrants invoke “due regard” to block subsequent incompatible or competitive activities? In a paper I recently published, I opined that due regard does not grant such an advantage. That interpretation would undermine the foundational principles of the OST—specifically Article I (freedom of use) and Article II (non-appropriation).
The OST does not define “due regard,” making its application ambiguous. Drawing parallels to the United Nations Convention on the Law of the Sea (UNCLOS), where the term denotes a reciprocal obligation to consider other States’ rights, the paper shows that “due regard” is not a unilateral privilege but a flexible duty of coordination. International tribunals interpreting UNCLOS have held that due regard requires States to balance competing interests and engage in meaningful consultation, depending on the nature of the rights involved and the potential interference.
Applied to outer space, the same balancing framework suggests that all actors—regardless of arrival order—must conduct activities with consideration for others. Physical realities, such as the limited availability of lunar sites suited for radio astronomy, mining, or water extraction, mean that incompatible uses are inevitable. However, the solution lies in coordination, not exclusion.
The paper warns that allowing early actors to use “due regard” as a shield to exclude others would effectively create territorial claims (contrary to Article II’s ban on appropriation) and would impede Article I’s freedom of use, particularly disadvantaging developing nations. It would also transform due regard from a cooperative principle into a competitive tool, contrary to the OST’s intent.
Ultimately, the paper concludes that the due regard obligation should be viewed not as a source of legal exclusivity, but as a procedural and substantive framework to ensure coordination, consultation, and peaceful coexistence in shared space environments. The first actor does not gain legal superiority; all actors are bound to exercise due regard reciprocally. This interpretation aligns with the OST’s core values and avoids undermining the equal access and freedom of exploration it seeks to protect.
Francesca Giannoni-Crystal, Due Regard Does Not Grant a Legal Early Entrant Advantage, 18 Boletín del Observatorio Jurídico Aeroespacial (B.O.J.A.) (Apr. 2025), https://www.hispaviacion.es/wp-content/uploads/2025/04/BOLET%C3%8DN-AEDAE-ABRIL-2025-v2.pdf
