What is the "retention principle" for priority claims?
The EPO as ISA must consider any priority claim to be valid if the international application claiming the priority right is filed within two months after expiry of the priority year ("retention principle"). Therefore, even if no request for restoration of right of priority has been filed, or if such request has been rejected or has not yet been decided upon at the time the international search is carried out, this has no bearing on the procedure before the ISA (see point 2.14.005).
Source: http://www.epo.org/applying/international/guide-for-applicants/html/e/ga_c3_2_6.html
Date retrieved: 17 May 2021