Where can I find detailed information about unity of invention under the Patent Cooperation Treaty (PCT)?

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.

Detailed information about unity of invention under the Patent Cooperation Treaty (PCT) can be found in MPEP Chapter 1800. Specifically, the following sections provide in-depth discussions:

• MPEP § 1850
• MPEP § 1875
• MPEP § 1893.03(d)

As stated in MPEP 823: “See MPEP Chapter 1800, in particular MPEP § 1850, § 1875, and § 1893.03(d), for a detailed discussion of unity of invention under the Patent Cooperation Treaty (PCT).”