What is the purpose of the Written Opinion in the PCT process?

The Written Opinion serves multiple purposes in the Patent Cooperation Treaty (PCT) process, as outlined in MPEP 1845:

“The international search report and written opinion together serve to inform the International Preliminary Examining Authority of the documents and arguments necessary to complete the relevant assessments if international preliminary examination is demanded, and to inform the designated Offices of information that may be relevant to examination in the national phase.”

Essentially, the Written Opinion provides a preliminary non-binding opinion on patentability, which helps guide further examination and informs national/regional patent offices during the national phase.

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Tags: international preliminary examination, National Phase, pct process, written opinion