Interstate compact

In the United States, an interstate compact is a pact or agreement between two or more states, or between states and any foreign government. The Compact Clause (Article I, Section 10, Clause 3) of the United States Constitution provides that "No State shall, without the Consent of Congress,... enter into any Agreement or Compact with another State, or with a foreign Power,..."[1]

The timing for Congressional consent is not specified by the Constitution, so consent may be given either before or after the states have agreed to a particular compact. The consent may be explicit, but it may also be inferred from circumstances. Congress may also impose conditions as part of its approval of a compact.[2] Congress must explicitly approve any compact that would increase the states' political power in a manner that would encroach upon the federal government's power.[3]

Most early interstate compacts resolved boundary disputes, but since the early 20th century, compacts have increasingly been used as a tool of state cooperation.[2] In some cases, an agreement will create a new multi-state governmental agency which is responsible for administering or improving some shared resource such as a seaport or public transportation infrastructure.

Interstate compacts are distinct from Uniform Acts, which are model statutes produced by non-governmental bodies of legal experts to be passed by state legislatures independently, rather than constituting an agreement among multiple states.

Treaties between the states, ratified under the Articles of Confederation during the period after American independence in 1776 until the current U.S. Constitution was ratified in 1789, are grandfathered and treated as interstate compacts. This includes agreements like the Treaty of Beaufort, which set the boundary between Georgia and South Carolina in 1787, and is still in effect.