Can an examiner rely solely on common knowledge for a rejection?

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.

No, an examiner cannot rely solely on common knowledge as the principal evidence for a rejection without supporting evidence in the record. The MPEP 2144.03 is clear on this point:

“It is never appropriate to rely solely on ‘common knowledge’ in the art without evidentiary support in the record, as the principal evidence upon which a rejection was based.”

This guidance is based on the Federal Circuit’s decision in In re Zurko, which held that:

“[T]he Board cannot simply reach conclusions based on its own understanding or experience—or on its assessment of what would be basic knowledge or common sense. Rather, the Board must point to some concrete evidence in the record in support of these findings.”

Examiners must provide specific evidence or reasoning to support their conclusions, even when relying on what might be considered common knowledge in the art.