A modus vivendi (Latin: "way of living") is a pragmatic diplomatic instrument used when parties cannot reach a definitive settlement but need a workable arrangement to manage their relations. Unlike a formal treaty, it is typically provisional, less detailed, and designed to be replaced or upgraded once conditions permit a more comprehensive accord.
In diplomatic practice, the term covers a spectrum of arrangements: written agreements explicitly labeled as such, exchanges of notes, tacit understandings, or even patterns of mutual restraint. The Vienna Convention on the Law of Treaties (1969) does not single out modus vivendi as a distinct category; whether one constitutes a binding international agreement depends on the intent of the parties and the language used, not on the label.
Classic functions include:
- Conflict management: freezing a dispute without prejudicing legal claims (e.g., over borders, sovereignty, or jurisdiction).
- Provisional regulation: governing trade, fisheries, or consular relations pending a fuller treaty.
- Face-saving: allowing governments to cooperate where domestic politics block formal recognition or ratification.
The device is particularly valued when one or both sides face ratification hurdles, when recognition issues are sensitive, or when the underlying dispute is too politically charged to resolve. Because a modus vivendi expressly avoids prejudicing legal positions, it can de-escalate tensions while preserving each party's maximalist claims for future negotiation.
For practitioners, the key drafting question is whether the arrangement is intended to create legal obligations or merely political commitments. Ambiguity on this point is sometimes deliberate. Researchers analyzing such instruments should examine the text, the circumstances of conclusion, and subsequent state practice to determine their actual legal status.
Example
The 1928 modus vivendi between the Holy See and France allowed the formation of diocesan associations to manage Church property, easing tensions left over from the 1905 separation of church and state.