Priority and the “same invention” (EPO, G 2/98, 2001)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

On a referral by the President of the EPO, the Enlarged Board of Appeal adopted a strict reading of the “same invention” requirement in Article 87(1) EPC: priority of an earlier application is to be acknowledged for a claim only if the skilled person can derive its subject-matter directly and unambiguously, using common general knowledge, from the previous application as a whole. The opinion rejects the approach of T 73/88, which had allowed priority despite the addition of a feature regarded as unrelated to the function and effect of the invention. It aligns the priority test with the disclosure test applied to novelty and amendments, which governs the effective date of each claim against intervening publications.

Facts and procedure

On 29 July 1998 the President of the EPO referred to the Enlarged Board, under Article 112(1)(b) EPC, a point of law on which the boards of appeal had given different decisions, in particular where a feature is added or more narrowly defined in the later application. A traditional line of case law applied a disclosure test (T 116/84, T 184/84, T 85/87, T 295/87), whereas T 73/88 “Snackfood/HOWARD” and the decisions following it allowed priority where the added feature did not change the character and nature of the invention.

The applicable law

Articles 87 to 89 EPC provide a complete, self-contained code of rules on claiming priority, and the EPC is a special agreement within the meaning of Article 19 of the Paris Convention (point 3). The Enlarged Board read Article 87(1) EPC in the light of Articles 4F and 4H of that Convention (point 4) and of Article 88(2) to (4) EPC, Article 88(4) corresponding almost literally to Article 4H (point 6.1).

Question

Does the “same invention” requirement in Article 87(1) EPC limit the right to priority to what is at least implicitly disclosed in the earlier application, or can a lesser degree of correspondence suffice?

Decision

The Enlarged Board equated the “same invention” with the “same subject-matter” referred to in Article 87(4) EPC (point 2) and found that strict reading consistent with Articles 4F and 4H of the Paris Convention (points 4 and 5) and with Article 88(2) to (4) EPC (point 6.8). For an “AND” claim combining features disclosed in two successive priority documents, multiple priorities cannot be claimed and the so-called “umbrella” theory is to be disregarded (point 6.6); for an “OR” claim, multiple priorities are acceptable where the generic term gives rise to a limited number of clearly defined alternative subject-matters (point 6.7).

Equal treatment of the applicant and third parties requires strictly the same criteria when determining which of two conflicting applications has the earlier relevant date under Article 54(3) EPC (point 8.1),, criteria which must also serve to identify the first application (point 8.2). Distinguishing between features related or unrelated to the function and effect of the invention lacks clear, objective criteria and would undermine legal certainty (point 8.3); for selection inventions, priority should not be acknowledged where the selection is novel under the EPO’s criteria (point 8.4). The Board concluded that priority is acknowledged only if the skilled person can derive the subject-matter of the claim directly and unambiguously, using common general knowledge, from the previous application as a whole (point 9).

Key points for practice

• Priority is assessed claim by claim, under the direct and unambiguous disclosure test applied to the earlier application as a whole (point 9).
• Adding, modifying or specifying a feature absent from the priority application deprives the claim of priority, whatever its role in the function of the invention (points 8.3 and 9).
• An “OR” claim using a generic term may enjoy multiple priorities for a limited number of clearly defined alternatives (point 6.7).
• Practical point: before relying on a patent exposed to an intervening publication, check that each claim asserted has a direct and unambiguous basis in the priority application.

Provisions applied

European Patent Convention

EPC 1973, Art. 54, 56, 60, 83, 84, 87, 88, 89, 93, 112, 123

Other instruments

Paris Convention, Arts 4A(1), 4C(4), 4F, 4H and 19; Rules of Procedure of the Enlarged Board of Appeal, Art. 11b

Case law cited

G 1/93; G 3/93; J 15/80; T 116/84; T 184/84; T 16/87; T 85/87; T 295/87; T 301/87; T 73/88; T 255/91; T 582/91; T 311/93; T 669/93; T 1056/93; T 364/95; T 77/97

Prepared by Dhenne Avocats from the text of the decision (epo.org, official English text), consulted on 11 October 2026. Only the official text is authoritative.