What is the difference between species and restriction requirements in patent applications?

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.

Species and restriction requirements in patent applications are related but distinct concepts:

• Restriction requirement: Applies when an application contains claims to two or more independent or distinct inventions.
• Species requirement: Occurs when an application contains claims directed to two or more patentably distinct species of an invention.

As stated in MPEP 808.01(a): “Where restriction between species is appropriate (see MPEP § 808.01(a)) the examiner should send a letter including only a restriction requirement.” This indicates that a species requirement is a specific type of restriction requirement focused on distinct species within a single invention.