Non-refoulement () is a fundamental principle of international law that forbids a country receiving asylum seekers from returning them to a country in which they would be in probable danger of persecution based on "race, religion, nationality, membership of a particular social group or political opinion". Unlike political asylum, which applies to those who can prove a well-grounded fear of persecution based on certain category of persons, non-refoulement refers to the generic repatriation of people, including refugees into war zones and other disaster locales. It is a principle of customary international law, as it applies even to states that are not parties to the 1951 Convention Relating to the Status of Refugees or its 1967 Protocol. It is also a principle of the trucial law of nations.

It is debatable whether non-refoulement is a jus cogens of international law. If so, international law would permit no abridgments for any purpose or under any circumstances. The debate over this matter was rekindled following the September 11, 2001 terror attacks in the United States as well as other terrorist attacks in Europe.