When can an examiner require restriction to a single species?

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.

An examiner can require restriction to a single species when multiple species are claimed and they are mutually exclusive. The MPEP 806.04(f) states:

“Where two or more species are claimed, a requirement for restriction to a single species may be proper if the species are mutually exclusive.”

This means that if the claimed species have distinct, non-overlapping characteristics, the examiner may issue a restriction requirement to limit the examination to a single species.