What is the “two-way distinctness” test for process and apparatus claims?

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.

What is the “two-way distinctness” test for process and apparatus claims?

The “two-way distinctness” test is a criterion used by patent examiners to determine whether process and apparatus claims are distinct for the purposes of restriction requirements. According to MPEP 806.05(e):

“Process and apparatus for its practice can be shown to be distinct inventions, if either or both of the following can be shown: (A) that the process as claimed can be practiced by another materially different apparatus or by hand; or (B) that the apparatus as claimed can be used to practice another materially different process.”

This test ensures that:

• The process is not solely dependent on the specific apparatus claimed
• The apparatus is not limited to performing only the claimed process

If either condition is met, the process and apparatus are considered distinct, potentially leading to a restriction requirement. This test helps maintain the integrity of the patent system by preventing overly broad claims that could unfairly limit competition or innovation.