When it is not possible to check the validity of the priority claim at the search stage, because:

then, for the purposes of drafting the search opinion, the priority claim will usually be assumed to be valid. Where at this stage the only objections which can be raised against the application depend on the priority being invalid, and the priority document (or its translation) is not available, the search division issues an entirely positive search opinion without objections. In case (ii) above, a communication according to Rule 53(3) may be issued as specified in A‑III, 6.8.1, and the validity of the priority subsequently reviewed in examination proceedings.

However, if an assessment of the validity of the priority claim is necessary as a result of intermediate prior art or potential state of the art according to Art. 54(3), and evidence is already available undermining the validity of the priority claim, then this needs to be brought up in the search opinion. For example, where the priority document is available at the time of drafting the search opinion and technical features of the claims are not present in the priority document, this may even be possible where a translation is required, but the search division is familiar with the language of the priority document (see also B‑VI, 5.3).

4.1 Use of "P" and "E" documents in the search opinion