In T 426/89 (OJ 1992, 172) claim 1 as granted and claim 1 of the main request related to a process for operating a pacemaker. The board noted that an actual operating method for a pacemaker for arresting a tachycardia would necessarily be a method for treating the human (or animal) body by therapy, and would not be patentable. However, the board agreed with the patentee that the claim referred to the steps in a technical method which did not define a method of treatment but rather, in functional terms, the structural features of a pacemaker. However, the board found the claim to be contrary to Art. 84 EPC 1973. The differences between the claim 1 according to the auxiliary request and the granted version were that in claim 1 the terms "Method for the operation of a pacemaker", had been replaced by "Pacemaker". The board held that claim 1 as granted was already a product claim containing a functional definition of a pacemaker. So the seeming change of category did not alter the content of the claim but simply served to clarify it (see also T 378/86, OJ 1988, 386).

In T 82/93 (OJ 1996, 274) claim 1 as granted related to a method of operating a pacer. The board found that this claim defined a method for treatment of the human body by therapy and therefore was not allowable under Art. 52(4) EPC 1973. It held that the device claim of the auxiliary request was not allowable under Art. 123(3) EPC 1973. The subject-matter protected by the granted claim was a pacer, when in use; in contrast, the claim of the auxiliary request only included technical features which defined physical characteristics of the pacer device itself. The board explained that in general terms, if a patent as granted only included claims defining the operation of a device and therefore containing both "device features" and "method features", and the proposals to amend the patent during opposition proceedings included claims which only contained "device features", the proposed amendment was not allowable having regard to Art. 123(3) EPC 1973, because the patent as granted conferred protection upon the device only when it was in use so as to carry out the method, whereas the proposed amended patent would confer protection upon the device whether or not it was in use, and would therefore confer additional protection compared to the patent as granted. In contrast to the findings in T 426/89, in the case at issue the board held that claim 1 as granted was clear, defined the use of a device to carry out a method of treatment of the human body by therapy and was not a pure "device claim" since it also included method steps. Thus, under such circumstances, Art. 52(4) and Art. 123(3) EPC 1973 might operate in combination as an "inescapable trap".