e) Priority and content of the priority document 

– Priority

In G 1/22 and G 2/22 (OJ 2024, A50), the Enlarged Board concluded that there is a rebuttable presumption under the autonomous law of the EPC that the applicant is entitled to claim priority, in accordance with Art. 88(1) EPC and the corresponding Implementing Regulations (G 1/22 and G 2/22, points 105, 112 of the Reasons and point I of the Order). The rebuttable presumption involves the reversal of the burden of proof, See also present chapter III.G.5.2.2e) and mainly chapter II.D “Priority” inter alia chapter II.D.2.4.1and II.D.2.4.3.

See chapter II.D "Priority" for the latest case law.

– Content of the priority document

In T 1147/02 the board dealt with the issue of which party to the appeal proceedings bore the burden of proving the exact content of a priority document in order to establish the relevant priority date. Since the appellant was the one to challenge the priority date necessary for establishing prior art, the principles elaborated in the case law of the boards of appeal dictated that the appellant also bore the burden of convincingly proving that the relevant date was not the filing date of the priority document.

In T 1303/18 (see Catchword), the patent proprietor held that the priority document D49 disclosed the same compound, meaning that the priority was valid. The board held that the patent proprietor bore the burden to prove that the compounds were identical. As a rule, any applicant filing an application claiming priority must ensure that the earlier application defines the same invention.