Editing Interference proceeding (section)

{{short description|US patent law procedure}}
{{more citations needed|date=October 2013}}

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 application]]s. Unlike in most other countries, which have long had a [[First to file and first to invent|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 file and first to invent|first-to-invent]]. The interference proceeding determines which of several patent applications had been made by the first [[inventor (patent)|inventor]].

The AIA switched the US to a first-to-file regime effective March 16, 2013,<ref>{{cite news |last1=Agostino |first1=Joseph |last2=Briggs |first2=Heath J. |last3=Schindler |first3=Barry J. |title=Phase 3 of the America Invents Act: New Patent Laws Take Effect on March 16, 2013 |url=https://www.natlawreview.com/article/phase-3-america-invents-act-new-patent-laws-take-effect-march-16-2013 |access-date=April 18, 2021 |work=National Law Review |date=February 2, 2013 |language=en}}</ref> and interferences apply only to patent applications with an effective filing date prior to that change.