17. Patentability

This chapter addresses the criteria for patentability; in other words, the rules patent examiners and courts use to decide if a patent is valid or not. These criteria are also useful in the context of an infringement action, because a defendant may make a counter-claim to revoke the claimant's patent for invalidity on the basis of one of the criteria. The patentability of an invention is defined by Articles 52–57 of the European Patent Convention. The criteria comprise five core elements: three positive and two negative. In terms of the positive requirements, for an invention to be patentable, it must possess novelty; inventive step; sufficiency and support; and industrial applicability. Regarding the negative criteria, the invention must not consist of excluded subject matter, and it must not fall afoul of any of the exceptions to patentability.