It may be noted that following G 2/98 (OJ 2001, 413) the older case law which devised the "disclosure" test still applies (see e.g. T 184/84, T 81/87, OJ 1990, 250, T 469/92, T 269/93, T 77/97). In T 311/93 and T 77/97 in particular, the boards applied the criterion of at least implicit disclosure used for the disclosure test under Art. 123(2) EPC 1973. On the other hand, G 2/98 rejected the approach taken in T 73/88 ("Snackfood", OJ 1992, 557; cf. also e.g. T 16/87, OJ 1992, 212; T 582/91; T 255/91, OJ 1993, 318; T 669/93; T 1056/93 and T 364/95), according to which adding non-essential and merely scope-limiting features did not invalidate a priority claim; see also "Case Law of the Boards of Appeal of the EPO", 3rd ed. 1998, p. 228 et seq. and 235 et seq.). The non-applicability of the "essentiality" criterion following G 2/98 was recently confirmed in e.g. T 1852/13 (with further references) and T 2466/13.

As was stated in G 2/98 (OJ 2001, 413), the extent of the right to priority is determined by, and at the same time limited to, what is disclosed in the priority application. Applying G 2/98, the board in T 923/00 found that the application as filed and the priority document were in essence identical. It emphasised that any conclusion in favour of or against the amendments' allowability under Art. 123(2) EPC 1973 would also apply in favour of or against entitlement to the claimed priority, and dealt with both issues jointly.

In its subsequent "disclaimer" decisions G 1/03 and G 2/03 (OJ 2004, 413 and 448), the Enlarged Board held that in order to avoid any inconsistencies, the disclosure as the basis for the right to priority under Art. 87(1) EPC 1973 and as the basis for amendments in an application under Art. 123(2) EPC 1973 have to be interpreted in the same way. That meant that a disclaimer, not providing a technical contribution as outlined, which was allowable during the prosecution of a European patent application does not change the identity of the invention within the meaning of Art. 87(1) EPC 1973. Therefore its introduction is allowable also when drafting and filing the European patent application without affecting the right to priority from the first application, which does not contain the disclaimer (see also T 175/03 and T 910/03). The Enlarged Board reaffirmed the importance of applying a uniform concept of disclosure in its further "disclaimer" decisions G 2/10 (OJ 2012, 376) and G 1/16 (OJ 2018, A70) – cf. "gold standard" disclosure test.

For the application of the disclosure test in the context of Art. 123(2) EPC, see chapter II.E. "Amendments".

The following qualification was made in T 282/12, a case which concerned "partial priority" (cf. also G 1/15, OJ 2017, A82): assessing priority by performing a test under Art. 123(2) EPC could lead to wrong conclusions in certain circumstances because the concept of “partial” validity of an amendment does not exist, whereas "partial priority" does (see also fuller summaries in chapters II.D.4.1. and II.D.5.3.3 below).