How is two-way distinctness determined for combination-subcombination inventions?

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.

Two-way distinctness for combination-subcombination inventions is determined by evaluating the inventions in both directions. According to MPEP 806.05(c):

“The combination as claimed does not require the particulars of the subcombination as claimed for patentability” (to show that the combination does not rely on the specific details of the subcombination), and

“The subcombination has utility by itself or in other combinations” (to show that the subcombination is not dependent on the combination).

If both of these statements are true, then two-way distinctness is established, and a restriction requirement may be proper if there are also reasons for insisting on restriction.