1.14.4 Shift in the interpretation of a claim by amendment of the description

In T 500/01 the board stated that a claim, the wording of which was essentially identical to a claim as originally filed, could nevertheless contravene the requirements of Art. 123(2) EPC 1973 if it contained a feature whose definition was amended in the description in a non-allowable way. The specific definition of a feature which according to the description was an overriding requirement of the claimed invention was applied by a skilled reader to interpret that feature whenever it was mentioned in the patent. Since in this case the definition had no basis in the application as filed, claim 1 did not meet the requirements of Art. 123(2) EPC 1973. See also T 471/20, in which the facts of the case were found to be different from T 500/01.

In T 1239/03 it was not in dispute between the parties that no part of the patent contained a definition of the ethylene content of the elastomeric copolymer in terms of weight percent. Prior to the amendment, preference was given to the interpretation "mol percent", which, with the deletion of example 3, had shifted towards "weight percent". In such a case, where it was certain that a shift in the interpretation of the claims had occurred, but uncertain if this would lead to an addition of subject-matter, the board took the view that it should be incumbent upon the patent proprietor or applicant as the author of such amendment(s) to demonstrate that the requirements of Art. 123(2) EPC 1973 were complied with in making them. In the case at issue, the patent proprietor was unable to do so. See also T 471/20, in which the facts of the case were found to be different from T 500/01.

In T 1227/10 the claim as granted was similar to the claim as originally filed. However, other than in the patent as granted, the original application also contained a figure 1 labelled as prior art and a corresponding passage of the description. The board found that the original application did not include the possibility of using a filter as gas solid separator for a certain purpose, whilst the patent as granted encompassed such a possibility. Hence, the deletion of original figure 1 and of the related passage of the description had modified the application in such a way that the granted claim 1 included subject-matter which was excluded from the originally filed invention.