In public international law, clausula rebus sic stantibus (Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 for "things thus standing") is the legal doctrine

Legal doctrine

A legal doctrine is a framework, set of rules, procedural steps, or test, often established through precedent in the common law, through which judgments can be determined in a given legal case. A doctrine comes about when a judge makes a ruling where a process is outlined and applied, and allows...

 allowing for treaties

Treaty

A treaty is an express agreement under international law entered into by actors in international law, namely sovereign states and international organizations. A treaty may also be known as an agreement, protocol, covenant, convention or exchange of letters, among other terms...

 to become inapplicable because of a fundamental change of circumstances. It is essentially an "escape clause" that makes an exception to the general rule of pacta sunt servanda

Pacta sunt servanda

Pacta sunt servanda , is a brocard, a basic principle of civil law and of international law.In its most common sense, the principle refers to private contracts, stressing that contained clauses are law between the parties, and implies that nonfulfilment of respective obligations is a breach of the...

(promises must be kept).

Because the doctrine poses a risk to the security of treaties as its scope is relatively unconfined, it requires strict regulations as to the conditions in which it may be invoked.

The doctrine is part of customary international law

Customary international law

Customary international law are those aspects of international law that derive from custom. Along with general principles of law and treaties, custom is considered by the International Court of Justice, jurists, the United Nations, and its member states to be among the primary sources of...

, but is also provided for in the 1969 Vienna Convention on the Law of Treaties

Vienna Convention on the Law of Treaties

The Vienna Convention on the Law of Treaties is a treaty concerning the international law on treaties between states. It was adopted on 22 May 1969 and opened for signature on 23 May 1969. The Convention entered into force on 27 January 1980. The VCLT has been ratified by 111 states as of November...

 under Article 62 (Fundamental Change of Circumstance), although the doctrine is never mentioned by name.