The Limits of Information Revelation in Multilateral Negotiations: A Theory of Treatymaking

States negotiate over the specific language of multilateral treaties because the exact provisions influence their willingness to ratify the treaty afterwards. In an extreme case, a state could fail to ratify a treaty it generally supported because the specific language was too far from what it sought. Those drafting treaties would like to uncover the minimal terms needed to secure the ratification of a key party, but will that party reveal those terms? Using a spatial representation of the issues in a treaty negotiation, we use mechanism design to determine what information states will reveal in a negotiation. We find that they are willing to reveal how they would like tradeoffs between different issues to be resolved but not the minimal terms they require for ratification. Further, negotiations cannot always separate types that need concessions to ratify from other types that would like concessions but would ratify the treaty even if they do not receive them.