The Unitary Patent (UP) has to be requested latest 1 months after the publication of the grant of a European Patent.
If certain formalities are not met, such a request for unitary effect may be rejected. The rejection may be pronounced by the European Patent Office (EPO) or by the Unified Patent Court (UPC).
Another example is a rejection of a request of a re-establishment of rights into the time limit for filing the request for the Unitary Patent.
In such a case, the final decision of the EPO or of the UPC, may be pronounced after the time limit for validating the patent in a participating member state or paying the national maintenance fees.
A so-called “safety net” system has thus been put in place by some participating member states to allow for validation of a European patent where a request for unitary effect has been rejected.
The safety net is regulated on the national level of the participating member states. Thus, it depends on the national provisions.
Currently all participating member states have provisions or plan to have provisions for a safety net except Luxembourg, Malta and Portugal. However, for Luxembourg exists a restoration procedure, which may be used within 20 months after a European patent has lapsed to non-payment of the annual fee.
The EPO has provided an overview with more details on its website that is regularly updated: https://new.epo.org/en/legal/national-measures-up/2022/ii/at.html? .