If the EPO considers that the claims of a patent application relate to more than one invention (i.e. lack "unity of invention"), then the applicant initially receives only a partial European search report. This partial search report is a search on the first invention in the claims, and is accompanied by an invitation to pay additional search fees to have the other invention(s) searched. It is not possible at the search stage to argue against the finding of lack of unity.
The paragraphs below set out the options available and factors to consider in deciding whether or not to pay additional search fees.
This information applies only to "direct" European patent applications. The situation is different for the European Regional Phase of international applications (as explained here).
If further search fees are not paid
The partial search report will be reissued as a final search report. In most cases the search report will be accompanied by a search opinion (see our separate information sheet on extended European search reports). In response to the search opinion it is possible to argue against the finding of lack of unity. If successful, then the EPO will conduct a further search if necessary, without charge. However, if the lack of unity finding is maintained by the Examining Division, then it will not be possible to have the unsearched inventions examined in the same patent application.
If further search fees are paid
The EPO will search those groups of inventions for which further search fees are paid (note that it is possible to pay only some of the extra search fees - see flow chart on PDF), and the combined search will be issued as a final search report. In most cases the search report will be accompanied by a search opinion (see our separate information sheet on extended European search reports). In response to the search opinion it is possible to argue against the lack of unity finding during examination. If the arguments are successful, then any extra search fees paid on inventions that are found to be unified will be refunded. If the arguments are unsuccessful, then only one of the searched inventions will be examined in the present application. The applicant has the choice of which of the searched inventions to select for examination.
If the Examining Division believes that the application contains multiple non-unified inventions at the time of substantive examination, then the objection of lack of unity of invention will be raised in an examination report.
If the non-unity objection is not overcome by argument in examination, then the application must be restricted to one searched invention only. The further invention(s) can be pursued in divisional applications, filed while the current application is still pending.
If a divisional application is filed directed to claims on which a search fee has already been paid on the present case, then the search fee paid for the divisional application will be refunded after filing.
This information must not be taken as a definitive statement of law or practice.