What is a classified search in patent examination?

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.

A classified search in patent examination refers to searching specific classification areas where the claimed subject matter of a patent application would be properly classified. According to MPEP 904.02(a):

“A search areas included in a proper field of search normally include the classification locations in which the claimed subject matter of an application would be properly classified at the time of the application’s classification or grant of a patent.”

This search method helps examiners efficiently locate relevant prior art by focusing on the most probable areas where similar inventions or technologies would be classified.