What is a constructive reduction-to-practice in the context of interference?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

A constructive reduction-to-practice in the context of interference refers to a description in an application that would have anticipated the subject matter of a count. MPEP § 2304.02(c) states:

“A description in an application that would have anticipated the subject matter of a count is called a constructive reduction-to-practice of the count. One disclosed embodiment is enough to have anticipated the subject matter of the count.”

Importantly, if an application is relying on a chain of benefit disclosures, the anticipating disclosure must be continuously disclosed through the entire benefit chain. The MPEP cites:

“See Tas v. Beachy, 626 Fed. App’x. 999, 1002 (Fed. Cir. 2015) (nonprecedential) (when a party to an interference seeks the benefit of an earlier-filed U.S. patent application, the earlier application must contain a written description of the subject matter of the interference Count, and must meet the enablement requirement.)”

Constructive reduction-to-practice is crucial in determining priority in interference proceedings, as it establishes the earliest date an invention was described in a patent application.