In the context of patents, an interference was a process used to determine which of two parties claiming a common invention was the first to invent it, also known as priority. Interference proceedings were necessary because the U.S. patent system followed a first-to-invent structure, rather than the first-to-file rule used in most other countries. The process could involve two applications or an application and an existing patent. Claims of interference had to be made within one year of the date that the application was published or that a patent was granted.
Interference proceedings have been largely eliminated due to the Leahy-Smith America Invents Act (AIA). This act, signed by President Obama on September 16, 2011, switched the U.S. patent system to one that followed the first-to-file rule. As such, any patent application filed on or after March 16, 2013 can no longer commence interference proceedings. Instead, interference proceedings were replaced with derivation proceedings. Additionally, the Board of Patent Appeals and Interferences was replaced with the Patent Trial and Appeal Board, to reflect the elimination of interference proceedings.
[Last updated in June of 2020 by the Wex Definitions Team]