Treaties may be:
- Bilateral- between two parties.
- Multilateral- between three or more parties.
Not surprisingly, the more parties there are to a treaty, the easier it usually is to find.
Treaties go by a dizzying variety of names, including accord, charter, concordat, constitution (of an international organization), covenant, final act, or pact. Certain names imply certain types of treaties:
- Convention- Generally implies a multilateral treaty setting forth broad rules of international law.
- Protocol- Generally implies a shorter, more specific treaty intended as an optional supplement or amendment to a larger multilateral treaty.
- Exchange of notes- A bilateral treaty accomplished by the exchange of documents from each country, rather than the signing of a single treaty. The text of the treaty consists of the exchanged documents, rather than a single consolidated text.
U.S. treaties are further divided into two types:
- Advice and consent or Article II treaties- treaties submitted to the Senate for their formal advice and consent, as established in Article II of the Constitution.
- Executive agreements- agreements signed by the President without the formal advice and consent of the Senate, further divided into:
- Congressional-executive agreements- agreements authorized either before or after the fact by a statute passed by Congress.
- Agreements pursuant to treaties- agreements authorized by prior treaties.
- Presidential or sole executive agreements- agreements made under the president's own authority, without the involvement of Congress.
Under international law, it is is generally irrelevant whether the U.S. passed a treaty through advice and consent or as an executive agreement. However, the distinction sometimes matters when locating the full-text of the treaty and matters when researching the history of a treaty's passage.
For more information on how U.S. treaties are passed, see the comprehensive study prepared by the Library of Congress' Congressional Research Service at the request of the U.S. Senate Committee on Foreign Relations and published as: