How does reduction to practice affect the determination of inventorship?

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.

Reduction to practice plays a crucial role in determining inventorship, particularly in cases of competing inventors. The MPEP 2138.05 provides guidance on this matter:

“The inventor of the subject matter of a patent is presumed to be the individual or individuals named as inventors in the patent. In order to rebut this presumption, clear and convincing evidence is required.”

Key points regarding reduction to practice and inventorship include:

• The first inventor to reduce the invention to practice (either actually or constructively) is generally considered the true inventor.
• In cases of simultaneous conception, the first to reduce to practice may be awarded priority.
• Corroborating evidence is often required to prove reduction to practice, especially in interference proceedings.

It’s important to note that mere conception without reduction to practice is insufficient to establish inventorship. Inventors must demonstrate that they have both conceived of the invention and reduced it to practice to secure their inventorship rights.