Adding matter or extending the subject-matter or content of a patent application with respect to the content initially filed is very important in the prosecution of a patent application, since it may have an adverse impact on the interests of the patent owner after the grant of the patent.

The addition of new matter usually occurs following an amendment made by the applicant to the application as originally filed, during the grant proceedings or prosecution of a patent application. During such prosecution, in order to overcome the examiner’s objections to the application, the applicant may be forced to amend a particular part of the application, usually the claims. It is possible that as a result of the amendment, new matter is included in the patent’s scope of protection that was not covered by the application as originally filed. Such amendment may introduce matter that extends beyond the content of the application as filed, whether because it ads, replaces or deletes technical features from the original application, which, as we have said, could adversely affect the owner after the grant.

Introducing content that extends beyond the original patent application is prohibited in article 48.5 of Spanish patent law 24/2015, of July 24, 2015 (LP 24/2015). Likewise, Article 123(2) of the November 2020 edition of the European Patent Convention (EPC) also prohibits the addition of content during the processing of a European patent application.

If during the processing of a patent application, the applicant includes new information (whether in the description, in the claims or in the figures) this can have an impact during a potential opposition to the patent granted. For example, article 43.c) of LP 24/2015 includes as a ground for opposition, where the subject-matter of the patent extends beyond the content of the application as filed. Article 100(c) EPC includes the same condition as a ground for opposing a European patent.

Moreover, the so-called “addition of subject-matter” can also lead to the revocation of a patent. According to article 102.1.c) of LP 24/2015, a cause of revocation of a Spanish patent (granted after the national or European proceeding) takes place when the subject-matter of the patent extends beyond the content of the application as filed. If the patent has been granted as a result of a divisional application or as a result of an application filed on the basis of article 11 (application filed by a non-entitled person), it may be revoked due to “addition of subject-matter” when the subject-matter of the European patent extends beyond the content of the application as filed.

In view of the above, it is evident that it is extremely important to pay attention to the amendments made during the prosecution of a patent application: if the amendments add new matter to the original application, it may be opposed and revoked and the owner will not be able to correct this defect once the patent has been granted. However, if the addition of new matter is detected in the first stage of the processing (pre-grant), either by the examiner or the actual applicant, the latter may probably be able to amend the claim, drawing or description in order to correct such addition of matter through a new amendment.

The guidelines for examination of the Spanish Patents and Trademarks Office (OEPMVersion 2.0 of July 2016) and of the European Patent Office (EPO – European Patent Office – H-IV; March version 2021) make reference to the extension of the subject matter of the application originally filed explaining when such subject matter is deemed to have been extended.

In light of the above, if the amendments made during the prosecution of a patent application extend the subject-matter of the application filed and the application is granted with such additional subject-matter, the applicant may face an unpleasant situation if a third party files an opposition or revocation claim. This is because pursuant to articles 48.6. of LP 24/2015 and article 123(3) EPC, it is impossible to amend a patent once it has been granted in such a way as to extend the protection it confers. An example of this would be if an applicant, during the grant proceedings of the patent application, includes in a claim a limitation that adds new subject-matter that was not part of the application as filed and that is finally approved by the examiner. During an opposition proceeding such limitation should be withdrawn from the claim pursuant to articles 48.5 LP 24/2015 and 123(2) EPC. However, withdrawing the limitation would breach articles 48.6. LP 24/2015 and 123(3) EPC, which would mean that the patent owner would lose the patent with or without the amendment and ultimately be trapped in a no-win situation (Art. 123(2)-(3) trap). Although it is true that the examiner in this situation would have approved the amendment, it must be borne in mind that the applicant is ultimately solely responsible for such amendments. The EPO’s Enlarged Board of Appeal indicated in its decision G1/93 in which cases it was possible to escape from the above trap. The EPO’s Board of Appeal has also issued various decisions regarding different aspects of adding subject-matter to European applications and patents, for example, T667/08, T823/96, T1125/07 and T99/13.

In addition to the importance of amendments made to a patent application during proceedings for the grant of the patent in or in a patent that has been granted, during the opposition or limitation procedure, it should also be borne in mind that such amendments can also be a determining factor in a revocation claim before a court. In particular, the Barcelona Provincial Appellate Court expressed its view on this ground for revocation at least in its judgments of March 29, 2019, December 15, 2020 and January 13, 2022.

Thus, where amendments are going to be made to a patent application, it is necessary to bear in mind the following indications of the EPO’s Guidelines for Examination regarding article 123(2) EPC, which have been taken into account and cited in the above-mentioned judgments:

  • “The underlying idea is that an applicant shall not be allowed to improve his position by adding subject-matter not disclosed in the application as filed, which would give him an unwarranted advantage and could be damaging to the legal security of third parties relying on the content of the original application (see G 1/93)”.
  • “An amendment is admissible if the subject-matter resulting from the amendment is directly and unambiguously derivable from the application as filed, i.e. where there is no doubt at all that subject-matter remaining is, be it explicitly or implicitly, directly and unambiguously disclosed in the application as filed.”
  • “It is impermissible to add to a European application subject-matter which the skilled person cannot derive directly and unambiguously, using common general knowledge, from the disclosure of the application as filed.”
  • “When assessing amendments, the focus is placed on what is really disclosed to the skilled person by the documents as filed”.

In conclusion, when making amendments during proceedings for the grant of a patent or during the opposition or limitation procedure, it is necessary to closely analyze whether they constitute a possible addition of subject-matter or new content. As mentioned, the addition of subject-matter can lead to the revocation of a patent both at the OEPM, at the EPO and even in court. To avoid adding subject-matter it is necessary to check, before making any amendments, that said subject matter is included in the originally filed application.