Pharmaceutical company J, which produces and sells prostate treatments, has suffered difficulties in business as a multinational pharmaceutical company M filed several injunction actions to patent infringement and damage actions. This patent belongs to the category of selective invention, and the patentability of the selective invention was at issue. It was not a favorable situation for J since at the patent invalidation trial, the inventive step of the patent in question was recognized. AIP represented at the appeal on the Supreme Court’s decision and brought the related patent dispute to an end by closely reviewing the legal principle of written description requirement of a selective invention, and finally invalidating M’s related patents. This case became a leading Supreme Court precedent regarding the written description requirement of selective invention.