專利要件在專利法中極為重要，此為專利制度的核心之一，因為其涉及專利之取得，即使在取得專利權之後，要行使專利權時，被控侵權人亦有可能主張專利要件不具備而遭認定專利權無效。專利要件中又以非顯而易知性最為困難，其不確定性最高。最近美國最高法院出現了有關非顯而易知性之KSR案件，有人稱該案為近年來最重要的專利法案件，因為其影響整個專利制度。KSR案件主要在探討Graham案及TSM法則，TSM法則的意義為何，TSM法則在實務上有何問題，KSR案件的主要內容為何，為何KSR案要探討TSM法則，KSR案代表之意義為何，KSR案之後實務上運作情形又如何，是本文探討之重點。

Patentability, as one of the fundamental elements of the patent system, is essential in the patent law. Patentability determines not only if a patent should be granted or not, but also a patent's validity when an infringement claim is brought up. Among the benchmarks for determining the patentability, non-obviousness is considered the most intriguing and uncertain issue. The decision of the US Supreme Court in KSR Infernational Co. v. Teleflex Inc. ("KSR".), which concerns non-obviousness, is said to be the landmark case in US patent law over the past few years. This case revisited the principles developed in Graham v. John Deere Co. of Kansas City, and the so-called Teaching, Suggestion, and Motivation (TSM) rules. In the following essay, I will first pursue what TSM rules connote, and what issues the application of TSM rules ahs created in the legal practice. Then I will look into the KSR and the connections between TSM rules and the KSR. Finally, I will try to explain the indications of the KSR, and its impacts on the legal practice.