What constitutes interfering subject matter in patent law?

Interfering subject matter in patent law occurs when the subject matter of one party’s claim would, if considered prior art, anticipate or render obvious the subject matter of another party’s claim, and vice versa. This is defined in 37 CFR 41.203(a), which states:

“An interference exists if the subject matter of a claim of one party would, if prior art, have anticipated or rendered obvious the subject matter of a claim of the opposing party and vice versa.”

In other words, interfering subject matter involves patentably indistinct inventions, often referred to as the “same invention” in patent law context.

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Topics: MPEP 2300 - Interference And Derivation Proceedings, MPEP 2301.03 - Interfering Subject Matter, Patent Law, Patent Procedure
Tags: Anticipation, Interfering Subject Matter, Obviousness, patent claims, same invention