Memorandum, agreement, treaty: what actually binds

LONDON —

Under the Vienna Convention on the Law of Treaties, what makes an instrument binding is not its name but whether the parties intended to create obligations under international law. A document called a “treaty” and one called an “arrangement” can have identical legal force — or wildly different force.

The reliable test is the language.

Binding instruments use shall, undertake, agree to, is obliged to. They name a date of entry into force, a ratification procedure, a withdrawal clause, and usually a dispute-settlement mechanism. They are registered with the UN Secretariat under Article 102 of the Charter.

Political commitments use will, intend to, plan to, are determined to. They speak of participants rather than parties, and come into effect rather than enter into force. Many memoranda of understanding say explicitly that they create no rights or obligations under international law.

This distinction is not a technicality, and it is not accidental. Governments choose the non-binding form on purpose: it avoids parliamentary ratification, it can be concluded quickly, and it can be abandoned without legal consequence. A great deal of contemporary security and technology cooperation is deliberately built this way.

So when an agreement is announced, the question is not how large the number attached to it is. It is whether anyone has promised anything a court could recognise — and, if not, what political cost failure would actually carry.