In T 281/86 (OJ 1989, 202), it was held that there is no requirement under Art. 83 EPC 1973 according to which a specifically described example of a process must be exactly repeatable. Variations in the constitution of an agent used in a process are immaterial to the sufficiency of the disclosure provided the claimed process reliably leads to the desired products. See also T 292/85 (OJ 1989, 275); T 299/86 date: 1987-09-23 (OJ 1988, 88); T 181/87, T 212/88 (OJ 1992, 28); T 182/89 (OJ 1991, 391) and T 19/90 (OJ 1990, 476).

In G 1/03 (point 2.5 of the Reasons) the Enlarged Board of Appeal indicated that a lack of reproducibility of the claimed invention is relevant under the requirements of sufficiency of disclosure if the technical effect is a technical feature of the claim, since then it is a feature characterising the subject-matter claimed (T 1079/08). A lack of reproducibility of the claimed invention (i.e. a failure of the claimed features to deliver the effect aimed for) is seen to represent, in the case of an effect which is not expressed in a claim but is part of the problem to be solved, "a problem of inventive step". If an effect is expressed in a claim, there is lack of sufficient disclosure (G 1/03, OJ, 2004, 413, and T 939/92, OJ 1996, 309, cited by T 2001/12; and more recently in T 1845/14).