Treaty

A treaty is an agreement under international law entered into by actors in international law, namely states and international organizations. A Treaty may also be known as: (international) agreement, protocol, covenant, convention,exchange of letters, exchange of notes, memorandum of understanding, etc. Regardless of the terminology, all of these international agreements under international law are equally treaties and the rules are the same.

However, in United States constitutional law, only a treaty that has achieved advice and consent of two-thirds of the United States Senate present is properly designated as a "treaty". If, instead, the President presents a negotiated instrument to the whole Congress for majority approval, the agreement is typically called a "congressional-executive agreement". For example, the North American Free Trade Agreement (NAFTA) and most other U.S. trade agreements are executive agreements.

Treaties can be loosely compared to contracts: both are means of willing parties assuming obligations among themselves, and a party to either that fails to live up to their obligations can be held liable under international law for that breach. The central principle of treaty law is expressed in the maxim pacta sunt servanda — "pacts must be respected". However, in the United States, treaties are equal in stature to legislation. Because of this rule, treaties and statutes can override each other—whichever is latest in time is controlling.