What happens if space objects launched into orbit cause damage? Who is held accountable in terms of international liability?

These questions are addressed by the Liability Convention, adopted by United Nations General Assembly Resolution 2777 and entered into force in September 1972.

As established by Article VII of the Outer Space Treaty (OST), States—or more precisely, launching States—are internationally liable for damage caused by their space objects. This created the necessity to elaborate more detailed provisions concerning the international liability of States in space.

The 1972 treaty defines the measures States must adopt to avoid causing damage to other States, individuals, or property, and establishes the need for internationally recognized procedures to handle damages caused by space objects.

Article I defines the term "damage," which encompasses loss of life, personal injury, or impairment of health. Article II, meanwhile, delineates the concept of the launching State, including any State that launches or procures the launching of a space object, or from whose territory or facility a space object is launched. The term "space object" includes both the spacecraft and its component parts.

Article III establishes the absolute liability of States for damage caused on the surface of the Earth or to aircraft in flight, whereas Article IV regulates damage occurring in outer space, such as collisions between space objects: in this scenario, liability arises only if negligence or fault on the part of the State is proven.

If two States cooperate in launching a space object and it causes damage to the surface of the Earth of a third State, the international liability of the two States is absolute; if the damage involves space objects, liability applies only in the event of proven fault. As governed by Article V, the third State can present a claim for compensation to the two launching States, which are jointly and severally liable. A joint launch can also include a State from whose territory the object is launched.

The procedures for claiming compensation are detailed in Articles IX–XII. The claim must be presented through diplomatic channels or, if both States are members of the United Nations, through the UN Secretary-General. The presentation must occur within one year following the date of the occurrence of the damage or the identification of the liable State. The amount of compensation is determined in accordance with international law and the principles of justice and equity.

Today, the Liability Convention remains one of the most critical instruments in international space law. Specifically, since the 2000s, the democratization of access to space has led to orbital saturation—often associated with the Kessler syndrome—with approximately 11,000 active satellites and over 20,000 space objects launched since the dawn of the space age in the 1950s. This scenario makes it paramount to update and integrate the regulations regarding State liability, as States also bear international responsibility for space activities conducted by private entities. Ensuring a clear framework of liability is essential for both security and international cooperation in outer space.