專利法賦予專利權人於特定期間內可排除他人未經其同意實施其專利權之權利。因此，對於取得專利權所須之要件須嚴加規範，以避免一般性或習知技術仍可得到專利制度之保護，否則既有違鼓勵發明創作之立法原意，也因其壟斷而造成產業科技水準停滯不前。觀察專利制度發展的歷史可以看出，在新穎性不足以維持專利制度正常運作下，逐漸發展出進步性之概念。為了防止那些技術人員日常例行的技術進步充塞各國專利審查機關以及平衡專利權的獨占性，美國在十九世紀中葉開始萌芽，起初係以判決形式出現，歷經百年直至1952年才納入美國專利法，法典化後概念雖然成熟，但適用上卻見仁見智，每個審查官與法官心中各有一把尺，使發明人無所適從。到了1966年美國最高法院在Graham v. John Deere案，對於進步性（非顯而易知性）才有比較一致的邏輯推理程序。首先，找出最相關的先前技術與系爭發明之請求項的差異之處，界定相關技術領域之平均技術水準以確定熟悉該項技術者，從熟悉該項技術者的觀點判斷不同之處是否顯而易知。而且，2007年4月，美國最高法院在KSR v. Teleflex案首次對美國聯邦巡迴上訴法院用於判斷組合發明之非顯而易知性所發展出的教示、建議、動機測試法（TSM）以及其所引發的爭議發表看法時，也再度闡釋Graham案的三階段判斷法則。本文使用大量舉例方式詳細說明美國最高法院提出Graham三階段判斷法則，以及CAFC所自行發展的TSM測試法的發展歷程與內容。接著，說明KSR案判決的要旨及對於非顯而易知性判斷的影響。最後，說明我國專利「進步性」與美國KSR案之「非顯而易知性」之比較。

Patent law gives the patentee a right in a specific period to exclude an implementation of his patent right by others without consent. Therefore, some requirements must to be possessed by the claimed invention to prevent general technologies or conventional skill from obtaining the protection of patent system, if not it will be contrary to the legislative intent of encouraging the invention and the creation, and the granted patent monopoly will cause a stagnation in the level of industrial technology. From the history of patent system development, we can find the concept of inventive step emerged from an insufficiency of maintaining the normal function of patent system by the requirement of industrial applicability and novelty.As to the requirement of non-obviousness of U.S. patent system, although not statutorily codified until §103 was enacted as part of the 1952 Patent Act, this concept has been recognized in U.S. patent case law since at least 1851. This ill-defined term proved incapable of precise application. The discrepancy in the mind of each examiner and judge confused the applicants. In 1966, the Supreme Court set out a framework for applying the statutory language of §103 in Graham v. John Deere Co., the rationale became relatively consistent. Under §103, the scope and content of the prior art are to be determined; differences between the prior art and the claims at issue are to be ascertained; and the level of ordinary skill in the pertinent art resolved. Also, in the April of 2007, the Supreme Court explained the "Graham standard" again in KSR when challenging TSM test developed by CAFC and its application for determining non-obviousness of the claimed invention. In this article, the back-grounds and contents of the "Graham standard" set by the US Supreme Court, and the "TSM test" developed by CAFC will be explained in detail. Next, the essential thoughts of KSR and the possible impacts to non-obviousness determination brought by the KSR opinion will be explained. Finally, the comparison between "non-obviousness" defined by KSR and "inventive step" of Taiwan's patent law will be explained.