7. Changes in relation to an established practice and interpretation

In G 2/07 (OJ 2012, 130) the Enlarged Board of Appeal stated that there can be no "legitimate expectation" that an interpretation of a substantive provision governing patentability given in a decision of the boards of appeal will not be overruled in the future by the Enlarged Board, since recognising such an expectation as legitimate would undermine the function of the Enlarged Board of Appeal. This holds particularly true for issues on which there is no solid body of decisions all to the same effect but where instead the relevant jurisprudence consists only of a very limited number of individual decisions, as is presently the case. In the past, the Enlarged Board has granted a transitional period in cases in which the Enlarged Board's decision has brought about a change in relation to an established procedural practice which the parties could not be expected to foresee. By contrast, for the reasons given above, the existence of "legitimate expectations" has never been acknowledged for issues before the Enlarged Board concerning the correct application, i.e. interpretation, of substantive patent law.

In opinion G 3/19, the Enlarged Board abandoned the interpretation of Art. 53(b) EPC previously arrived at in G 2/12 but held that its new interpretation (in G 3/19) was not retroactive.