In United States patent law, an interference proceeding, also known as a priority contest, is an inter partes proceeding to determine the priority issues of multiple patent applications.
Unlike in most other countries, which have long had a first-to-file system, until the enactment of the Leahy-Smith America Invents Act (AIA) in 2011, the United States operated under a first-to-invent.
The interference proceeding determines which of several patent applications had been made by the first inventor.
Appeals from this tribunal are heard before either the United States Court of Appeals for the Federal Circuit or the United States District Court for the District of Columbia.
41.207(a): On September 16, 2011, President Obama signed the Leahy-Smith America Invents Act into law.