What are the requirements for a proper restriction between 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.

For a proper restriction between species, the following requirements must be met:

• There must be no disclosure of a relationship between species (see MPEP § 806.04(b))
• There must be a patentable difference between the species as claimed
• There would be a serious search and/or examination burden on the examiner if restriction is not required

As stated in MPEP 808.01(a): “Where there is no disclosure of a relationship between species (see MPEP § 806.04(b)), they are independent inventions. A requirement for restriction is permissible if there is a patentable difference between the species as claimed and there would be a serious search and/or examination burden on the examiner if restriction is not required.”