How does the USPTO determine the field of search for a patent application?

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.

The USPTO determines the field of search for a patent application based on the claimed subject matter and its classification. MPEP 904.02(a) states:

“The field of search should extend to all probable areas relevant to the claimed subject matter and should cover the disclosed features which might reasonably be expected to be claimed.”

This means that examiners consider:

• The subclass where the claimed subject matter would be classified
• Analogous areas of domestic and foreign classification
• Disclosed features that might be claimed
• Probable areas relevant to the claimed subject matter

By considering these factors, examiners can conduct a comprehensive search that covers all relevant areas of prior art.