a) Earlier case law of the boards of appeal: the "contribution approach" 

In order to assess whether the claimed subject-matter was an invention within the meaning of Art. 52(1) EPC 1973, the boards of appeal applied, in their earlier case law, the so-called "contribution approach", according to which an invention had a technical character if it provided a technical contribution to the state of the art in a field not excluded from patentability under Art. 52(2) EPC 1973 (see T 121/85, T 38/86, OJ 1990, 384; T 95/86, T 603/89, OJ 1992, 230; T 71/91, T 236/91, T 833/91, T 77/92). The idea behind the so-called contribution approach was that the EPC 1973 only permitted patenting "in those cases in which the invention involves some contribution to the art in a field not excluded from patentability" (T 38/86, OJ 1990, 384). In other words, in order to assess the first requirement, i.e. the presence of an invention within the meaning of Art. 52(1) EPC 1973, a criterion was established which relied on meeting further requirements mentioned in that Article, in particular novelty and/or inventive step. Thus, some prior art was taken into account when determining whether subject-matter was excluded under Art. 52(2) and (3) EPC 1973 (T 258/03, OJ 2004, 575; see T 769/92, OJ 1995, 525).