Find United States Treaties
Prior to 1950, U.S. international agreements were published in the United States Statutes at Large (Stat.).
From 1950 to 2005, U.S. treaties are published in slip form in the Treaties and Other International Acts Series (T.I.A.S.). From 1950 until 1982, these slip opinions were compiled and published in the United States Treaties and Other International Acts (U.S.T.). Addtionally, the Treaty Series (T.S.), which was a precursor to the T.I.A.S. series, covered Article II treaties from 1795 to 1945. These titles can be found in HeinOnline's U.S. Treaties and Agreements Library.
Since 2006, T.I.A.S. is no longer published in print and can instead be found on the State Department's website.
Last, Treaties in Force is an index of U.S. treaties containing information on when particular treaties came into force, who the parties to the agreement are, and whether a party state entered a reservation or declaration. Treaties in Force can be found on the State Department's Office of Treaty Affairs website and in HeinOnline's U.S. Treaties and Agreements Library.
Find Congressional Documents Ratifying a Treaty
The U.S. Constitution grants the president the power to enter into treaties, but the treaty must be ratified by a two-thirds vote of the U.S. Senate in order to become effective and enforceable. U.S. Const. art. II § 2.
When the president sends a treaty to the Senate for ratification, it is printed as a Treaty Document. Prior to the 97th Congress (1981-82), a treaty sent to the Senate was printed as a Senate Executive Document. Once sent to the Senate, treaties are referred to the Senate Committee on Foreign Relations, which conducts public hearings and issues recommendations in the form of Senate Executive Reports.
These documents can be found on Congress.gov, Govinfo.gov, and ProQuest Congressional.
Find Other Treaties
The United Nations Treaty Series (U.N.T.S.) publishes treaties from all United Nations member states, including the U.S., going back to 1946. Prior to that, the League of Nations Treaty Series (L.N.T.S.) published treaties registered with the Secretariat of the League of Nations between 1920 and 1946. Additionally, Multilateral Treaties Deposited with the Secretary-General is a United Nations publication that tracks the status of over 500 treaties and includes information on signatories and ratification and the texts of reservations, declarations, and observations.
All three publications can be found online in the United Nations Treaty Collection and in HeinOnline's United Nations Law Collection.
The Consolidated Treaty Series (C.T.S.) contains the text of international agreements from 1648 to 1919. It is available in print on the Law Library's Mezzanine (Call No. KZ120 .P35). Similar content--including the names of international agreements and their C.T.S. citations--is available through Oxford Historical Treaties.
Historical, national, and regional treaty collections may be available online. See Georgetown's Guide to Free Online Treaty Collections as a starting point.