ABSTRACT
When ascertaining the extent of the monopoly claimed, the courts had in mind that the purpose of the claims was to give the patentee protection and at the same time to give a reasonable amount of certainty to the public. In Catnic Components Ltd v Hill and Smith (1982), the House of Lords considered a claim involving a lintel used in load bearing. The defendants used a similar lintel, differing in the angle of alignment. The defendants claimed that their variant was not an infringement of the patentee’s claim of a vertical lintel if construed literally, since their lintel stood at a slight angle. They also denied ‘pith and marrow’ infringement, since the perpendicular stance was a functional requirement of any lintel. The House of Lords in considering the matter found the patent infringed on the basis that the term ‘vertical’ meant ‘vertical or sufficiently close to vertical to be able to perform the same functions as it would have done if it were vertical’.
