R. 28(d) EPC (R. 23d(d) EPC 1973) provides that European patents should not be granted in respect of processes for modifying the genetic identity of animals which were likely to cause them suffering without any substantial medical benefit to man or animal, and also animals resulting from such processes.

One of the most important cases dealing with interpretation not only of R. 23d EPC 1973, but also of Art. 53(a) EPC, concerned a patent relating to transgenic animals having an increased probability of developing cancer. The application resulted in two groundbreaking board decisions: T 19/90 (OJ 1990, 476, see below), in which the matter was remitted to the department of first instance, and T 315/03 (OJ 2006, 15), in which a patent was granted on the basis of new claims.

Having addressed the relationship between R. 23d EPC 1973 (R. 28 EPC) and Art. 53(a) EPC (see also in this chapter I.B.2.), the board in T 315/03 turned to the test under R. 23d(d) EPC 1973 (R. 28(d) EPC). This test required only three matters to be considered: animal suffering, medical benefit and the necessary correspondence between the two in terms of the animals in question. The board observed that the test was to be applied to ensure that a patent extended only to those animals whose suffering was balanced by a medical benefit. The level of proof was the same for both animal suffering and substantial medical benefit, namely likelihood (see also T 1262/04 of 13 July 2012 date: 2012-07-13).