Entry into force (EIF) conditions are the provisions in a treaty that determine the moment it produces legal effects for its parties. Under Article 24 of the 1969 Vienna Convention on the Law of Treaties (VCLT), a treaty enters into force "in such manner and upon such date as it may provide or as the negotiating States may agree." Absent such a clause, it enters into force when consent to be bound has been established for all negotiating states.
Common EIF formulas include:
- Threshold ratifications: A fixed number of states must deposit instruments of ratification, acceptance, approval, or accession. The Rome Statute required 60 ratifications (Article 126) and entered into force on 1 July 2002.
- Weighted or qualitative thresholds: Beyond a numerical floor, the treaty may require specific categories of states. The Comprehensive Nuclear-Test-Ban Treaty (CTBT) requires ratification by all 44 "Annex 2" states and has not yet entered into force.
- Emissions or capacity thresholds: The Paris Agreement required ratification by at least 55 parties accounting for at least 55% of global greenhouse gas emissions; it entered into force on 4 November 2016. The Kyoto Protocol used a similar dual test and entered into force on 16 February 2005.
- Fixed date or deposit-plus-delay: Many treaties enter into force a set number of days after the threshold is met (often 30, 60, or 90 days), giving administrations time to prepare.
- Bilateral exchange: Bilateral treaties typically enter into force upon exchange of instruments of ratification or upon notification that domestic procedures are complete.
For states joining after general EIF, the treaty usually enters into force individually on a date tied to their own deposit. Provisional application under VCLT Article 25 can give effect to a treaty before formal EIF, as occurred with parts of the Energy Charter Treaty. EIF conditions are politically significant: they balance the drafters' desire for broad participation against the risk that a small group of holdouts can indefinitely block a regime, as the CTBT illustrates.
Example
The Paris Agreement entered into force on 4 November 2016, thirty days after the dual threshold of 55 parties and 55% of global emissions was crossed when the EU, India, and others deposited their instruments in October 2016.
Frequently asked questions
It remains a signed but non-binding instrument. The CTBT, opened for signature in 1996, has 187 signatories but has not entered into force because several Annex 2 states have not ratified.
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