Use invention of a chemical substance

The Japanese Patent Law defines the patentable subject matter and considers the following types or categories of inventions 'a thing (substance)', 'a method' and 'a method of producing a thing (substance)'; however 'use' as a category is lacking. Although a discovery per se is unpatentable, the discovery of a new use of a product is practically patentable in a claim within the category of 'a thing' or 'a method'. Two or more use inventions are deemed to be identical if those uses are substantially undistinguishable from one another with respect to 'the range within which they are applied', 'means of application of the use' and 'time of application of such use', even when the intended uses are different. An invention of use in the field of pharmaceutical products is patentable in the form of a claim: 'substance or composition coupled with the indication of the intended pharmaceutical use'. Under the 'Guidelines for practice in examining pharmaceutical inventions' two or more inventions of pharmaceutical uses of one product are regarded as being identical if (A) the pharmacological effects are based on the same or closely related pharmacological action, or if (B) they are substantially undistinguishable in 'the range of applications'. Actually, the guideline is not practised so strictly, particulary with respect to the standpoint (B). Problems are also left unsolved in Japan in pharmaceutical use inventions with respect to the entity of the patent right granted and to the preservation of right and further how to judge infringement, due to the fact that the subjects of application are human beings. For solving these problems some means can be contrived: 'method of curing disease' is deemed to be patentable subject matter, or a generic claim is granted on the first use and a specific claim is granted on the second use. Also in Japan various opinions exist as to whether the so-called second use should be patentable subject matter or not and in which form the second use, if patentable, should be patented.