Rebus sic stantibus (Latin: "things thus standing") is a principle of treaty law allowing a party to invoke a fundamental change of circumstances as a ground for terminating or withdrawing from a treaty. It is codified in Article 62 of the Vienna Convention on the Law of Treaties (1969), which deliberately frames the doctrine in narrow, negative terms: a change of circumstances may not be invoked unless (a) the existence of those circumstances constituted an essential basis of the parties' consent, and (b) the change radically transforms the extent of obligations still to be performed. Article 62 also excludes invocation for treaties establishing a boundary, or where the change results from the invoking party's own breach.
The doctrine stands in tension with pacta sunt servanda—the foundational rule that treaties must be observed in good faith. Tribunals have therefore applied it sparingly. In the Fisheries Jurisdiction case (UK v. Iceland, 1973), the International Court of Justice acknowledged Article 62 as reflecting customary international law but rejected Iceland's invocation. Similarly, in the Gabčíkovo-Nagymaros case (Hungary/Slovakia, 1997), the ICJ ruled that political and economic changes following the end of the Cold War did not meet the high threshold, reaffirming the doctrine's exceptional character.
For diplomats, rebus sic stantibus functions less as an everyday legal tool than as a rhetorical and negotiating device. States invoke it—often loosely—to justify reopening obligations they find burdensome, ranging from arms-control agreements to bilateral investment treaties. Effective tradecraft requires distinguishing genuine fundamental change (e.g., dissolution of a counterparty state, collapse of an essential factual premise) from ordinary shifts in policy preference, which the doctrine does not cover.
Example
In the Gabčíkovo-Nagymaros case (1997), Hungary invoked rebus sic stantibus to justify abandoning a 1977 dam treaty with Czechoslovakia, but the ICJ rejected the argument.