‘Due Regard’ and the Evolving Law of Outer Space Operations

On Dec. 17, 2025, the Congressional Study Group on Foreign Relations and National Security convened in person on Capitol Hill to discuss the evolving international law of outer space operations and the “due regard” principle. The prospect of a substantial number of human beings operating in outer space—for scientific, commercial, and military purposes, among others—has rapidly gone from the realm of science fiction to an imminent reality. But both international law and the domestic legal regimes governing public and private sector activities in outer space were designed for an earlier era, and efforts at reform are struggling to keep pace with scientific advancements. Instead, the rules governing early outer space operations—and the terrain on which later, more formal legal regimes will be built—are likely to be defined through the practice of states and associated non-state actors.

For the session, coordinator Scott R. Anderson led an initial discussion with two distinguished scholars in space law:

• Andrea Harrington, associate professor in the McGill Faculty of Law and the co-director of its Institute of Air and Space Law, who previously served as the dean of space education at Air University for the U.S. Space Force; and
• Michelle Hanlon, assistant professor of practice at the University of Mississippi School of Law and executive director of its Center for Air and Space Law, as well as the co-founder and president of the nonprofit For All Moonkind, which focuses on obtaining international legal recognition for and protection of human cultural heritage in outer space.

Background readings circulated before the session included:

• Symposium on “Returning to the Moon: Legal Challenges as Humanity begins to Settle the Solar System,” 9 Global Business Law Review 1, 71-91 (2021) (transcript of panel on “How Will We Govern a Moon Village?”);
• Andrea Harrington, “Due Regard as the Prime Directive for Responsible Behavior in Space,” 20 Loyola University of Chicago International Law Review 57 (2023); and
• Michelle Hanlon, Testimony on “The Mineral Supply Chain and the New Space Race” before the House Committee on Natural Resources’ Subcommittee on Oversight and Investigations (Dec. 12, 2023) (congressional testimony).

The session began with an overview by Harrington of the 1967 Outer Space Treaty and its ninth article, known as the due regard principle, which obliges states to consult one another in good faith when their activities in space might cause harmful interference to another state’s space operations. Harrington pointed out that the due regard principle exists in other legal contexts, particularly maritime law, yet the principle has been neglected and inconsistently applied in space. Amidst heightened concern over security and sustainability in space following an uptick in human activity, the due regard principle may present an opportunity for states to shape the nature of their future interactions in outer space.

Harrington said one way the United States could have a greater voice in crafting obligations in space is by invoking due regard in outer space disputes and adopting the principle into U.S. policies and law. With ambiguity surrounding what activities conflict with the principle, signaling to other states when the United States interprets an act as clashing with or complying with due regard could allow the United States to influence how the principle is implemented internationally.

Hanlon then gave a brief introduction to her work with For All Moonkind, a nonprofit organization that advocates to preserve artifacts of human history in space. Hanlon explained how the due regard principle could be used as a framework to protect historically significant areas in space, citing the One Small Step Act as an example where Congress had applied due regard to protect the landing sites of the Apollo missions on the moon from commercial interference. She noted that the principle has likewise informed broader U.S. efforts to develop rules around space operations, including through the Artemis Accords.

Hanlon detailed one variable that complicates adherence to the due regard principle—landings on the lunar surface eject a dust-like material, called regolith, which blankets large areas of the surface. There are dozens of missions planned to the moon by 2030, with most set to land on the lunar south pole. This means missions will likely impact each other as regolith is displaced during the landing process onto other nearby missions. Yet it remains unclear how actors will execute their missions while minimizing negative impacts on others. The United States, Hanlon suggested, could use these landings as an opportunity to further establish its record of invoking due regard by implementing the principle into the policies and laws regulating lunar activity.

The session then concluded with an open discussion wherein attendees were invited to ask questions or present their own views on some of the issues raised.