A patent interference is an inter partes proceeding to determine which party was the first to invent commonly claimed subject matter. An interference is also a viable procedure for challenging the validity of an issued patent or otherwise allowable claim(s) under virtually any theory of invalidity—provided that the challenged claims have an effective filing date of earlier than March 16, 2013. Applications with an effective filing date of March 16, 2013, or later are not subject to interference proceedings.
The only party that has standing to initiate or request an interference is an applicant with a pending patent application that contains allowable claims toward the same or substantially the same invention claimed in another pending application or unexpired patent. In addition, a patent examiner can initiate an interference proceeding sua sponte if the claims are otherwise allowable.
Once declared, the Patent Trial and Appeal Board (PTAB) conducts the interference proceeding in two stages to determine which party was the first to invent the commonly claimed (i.e., interfering) subject matter. During the preliminary phase, each party can challenge the validity or patentability of the opponent’s claims involved in the interference on almost any basis—including prior art, support, and derivation. This preliminary phase may also include limited discovery such as expert witness depositions. At the conclusion of the preliminary phase, the PTAB issues a decision on the validity or patentability of each challenged claim. If all of a party’s involved claims are declared invalid or unpatentable, the interference is concluded with the surviving party being awarded priority of invention.
If each party has at least one claim that survives the preliminary phase, the PTAB conducts the priority phase to determine which party was the first to invent the commonly claimed subject matter. The priority phase also includes limited discovery—including expert witness depositions and the exchange of highly confidential documents such as invention records, internal communications, and inventor notebooks—for each party to establish its earliest possible dates of conception and/or reduction to practice.
Where applicable, patent interferences provide a substantial benefit for challenging ownership of a patent where the only alternative may be litigation.