The appellant instituted action against the first respondent based on the alleged infringement of its patent. The firstrespondent denied such infringement and counterclaimed for revocation of the patent on grounds of, inter alia, lackof novelty and obviousness. The patent had 15 claims of which claims 2 to 12 were directly or indirectly dependenton claim 1 while claim 13, although based on claims 1 to 7, contained an added aspect that was, for the purposes ofthis judgment, of special importance. The Commissioner of Patents was called upon to consider the issues of validityand infringement in relation to claim 1 only. He concluded that claim 1 was valid and infringed, and issued acertificate of validity.