The Enlarged Board of Appeal (EBoA) at the EPO has in a recent decision of 22 June clarified the principle of the prohibition on double patenting. The principle of the prohibition on double patenting excludes two patents being granted to the same applicant for one invention.

The Examining Division applied this principle and refused European patent application No. 10718590.2 under Articles 97(2) and 125 EPC on the ground that the applicant already had a patent for the same invention, following an assessment that claim 1 was “100% identical” to the subject-matter claimed in the patent from which 10718590.2 claimed priority.

The decision was appealed by the applicant, who argued in his appeal that the prohibition did not apply to a situation of internal priority. The applicant argued that decisions G 1/05 and G 1/06 on double patenting related to divisional applications and therefore applied only in that context and not in the context of internal priority. Decision T 1423/07 recognised that the applicant had a legitimate interest in obtaining two patents with the same scope, a longer term of protection being available to the applicant as a result of the claiming of an internal priority, since the term of the patent is calculated on the basis of the filing date of the patent application. The applicant therefore argued that there was no proper legal basis for prohibiting double patenting, and that there existed a legitimate interest in obtaining a patent with a later filing date in order to increase the term of the patent.

The Technical Board of Appeal 3.3.01, which handles pharmaceutical matters, referred three questions on the prohibition on double patenting to the Enlarged Board of Appeal (T 318/14, OJ EPO 2020, A104):

1. Can a European patent application be refused under Article 97(2) EPC if it claims the same subject-matter as a European patent which was granted to the same applicant and does not form part of the state of the art pursuant to Article 54(2) and (3) EPC?

2.1 If the answer to the first question is yes, what are the conditions for such a refusal, and are different conditions to be applied depending on whether the European patent application under examination was filed

1. a) on the same date as, or
2. b) as a European divisional application (Article 76(1) EPC)

      in respect of, or

1. c) claiming the priority (Article 88 EPC) in respect of a

      European patent application on the basis of which a European

      patent was granted to the same applicant?

2.2 In particular, in the last of these cases, does an applicant have a legitimate interest in the grant of a patent on the (subsequent) European patent application in view of the fact that the filing date and not the priority date is the relevant date for calculating the term of the European patent under Article 63(1) EPC?

After having analysed several provisions of the European Patent Convention with respect to their suitabilities as proper legal basis for the prohibition on double patenting, the EBoA concluded that Article 125 EPC, although providing that “a procedural provision which is absent from the European Patent Convention but which may be established with the help of a principle of procedural law generally recognized in the Contracting States”, may also extend to substantive issues. Therefore, from a purely systematic point of view, Article 125 EPC may provide a legal basis for the regulation of double patenting – whether this means permitting or prohibiting it – even though a consideration of substantive issues may be involved as well.

The EBoA was, however, unable to conclude that the prohibition on double patenting is a principle generally recognised in the Contracting States and therefore had to recourse to the preparatory documents of the convention (the “travaux préparatoires”) for an answer as to whether double patenting is permitted or prohibited.

According to the minutes of the Proceedings of Main Committee I during the Diplomatic Conference in 1973, point 665., a common agreement that double patenting was not possible was already reached. With regard to double patenting, the minutes state that:

“In connection with Article 125, it was established at the request of the United Kingdom delegation that there was majority agreement in the Main Committee on the following: that it was a generally recognised principle of procedural law in the Contracting States that a person can be granted only one European patent for the same invention in respect of which there are several applications with the same date of filing.”

The EBoA found that since the competent legislator, here the Diplomatic Conference, established that the prohibition on double patenting was a generally recognized principle as a question of fact, and in addition made it clear that this was a principle falling under Article 125 EPC as a matter of interpretation of the law, the European Patent Office was thereby not only empowered to apply this principle, but effectively also duty-bound to do so.

It was therefore concluded that a European patent application can be refused under Article 97(2) EPC if it claims the same subject-matter as a European patent which was granted to the same applicant and if it does not form part of the state of the art pursuant to Article 54(2) and (3) EPC. Question 1 was thus answered in the affirmative.

With regard to question 2.1, the EBoA concluded that the agreement in point 665. of the minutes of the Proceedings of Main Committee I during the Diplomatic Conference in 1973 is not to be read as a legal provision in the usual sense, but rather as what it was intended to be, namely the expression of a general principle. Therefore, the agreement cannot be expected to have been formulated with the precision of a legal provision. Against this background, the EBoA considers that the requirement of the “same date” as stated in point 665. is to be understood as the same “effective date”, such that applications with a common priority are also covered by the prohibition of double patenting.

The EBoA further noted that in the context of divisional applications, a provision prohibiting claims directed to the same subject-matter had been deleted from the draft EPC, and that this provided support for the prohibition being of a more general nature. In Article 137a(2) of the draft EPC relating to divisional applications, the wording “The claims of the earlier application and any divisional application shall exclude the matter for which protection is sought by any of the other applications” was removed. Although this could be construed as endorsing the possibility of claiming identical subject-matter, the German version of the minutes of the Proceedings of Main Committee I during the Diplomatic Conference in 1973 makes it clear that this deletion was made to prevent any inverse conclusion that only divisional applications had to be directed to different subject-matter, whereas other applications of the same applicant were permitted to claim the same invention.

The EBoA therefore considers that the preparatory documents do not point to any special circumstance or condition inherent in the identified constellations which would lead to the conclusion that any of the three constellations of question 2.1 should be treated differently from the others with respect to the prohibition on double patenting.

To summarize, the questions referred to the EBoA were answered as follows:

1. A European patent application can be refused under Articles 97(2) and 125 EPC if it claims the same subject-matter as a European patent which has been granted to the same applicant and does not form part of the state of the art pursuant to Article 54(2) and (3) EPC.

2.1 The application can be refused on that legal basis, irrespective of whether it

1. a) was filed on the same date as, or
2. b) is an earlier application or a divisional application (Article 76(1) EPC) in respect of, or
3. c) claims the same priority (Article 88 EPC) as the European

      patent application leading to the European patent already

      granted.

2.2 In view of the answer to Question 2.1 a separate answer is not required.

However, even though the EBoA with decision G4/19 has clarified the principle of the prohibition on double patenting, some questions remain unanswered:

1. Does “same subject-matter” in the context of double patenting mean “identical subject-matter” rather than “mostly overlapping subject-matter”? If so, could an applicant make minor amendments to the claims of a second application to make the claims not identical to the claims already granted and thereby obtain a second patent with essentially the same scope of protection?
2. Does “same applicant” mean that if, say, a divisional application is transferred to a subsidiary, then even identical subject-matter will not be considered double patenting?
3. In its Reasons for the Decision, the EBoA considers that the reference to Article 97(2) EPC makes it clear that the referred question is restricted to (the applicability of the prohibition during) substantive examination proceedings under Article 94 EPC before the Examining Division. Hence, it seems that G 4/19 only applies to Examination and not to Opposition. If so, can the claims during Opposition be amended to an identical subject matter as an already granted patent?