Book excerpt: As reflected in the Federal Circuit's fractured opinion in CLS Bank v. Alice Corp., there is no greater confusion in contemporary patent law than that surrounding the scope of patent eligibility limitations. This Supreme Court amicus brief in that case traces the roots of the court-made doctrines excluding patents on laws of nature, physical phenomena, and abstract ideas. It argues that a test of inventive application neither serves the underlying purposes of the patent system nor comports with the process of modern technological advance. As a result of advances in scientific understanding and methods over the past 150 years, many if not most inventions today explicate, manipulate, and control physical, chemical, biological, and digital phenomena at elemental, molecular, algorithmic, and systemic levels. Doctrines that treat conventional application of even newly discovered computer algorithms, molecular pathways, and chemical synthesis as unpatentable threaten to exclude much of the inventive thrust of modern research. Mayo's requirement for unconventional application shifts scientists' efforts from the valuable scientific and technological advances that society seeks toward surmounting an amorphous test of non-obvious implementation. Specific and practical application, in conjunction with the technological arts limitation explicated in Justice Stevens's concurrence in Bilski, would better serve as the test for patent eligibility in the modern scientific and technological age. Particularly in light of past experience, setting inventive application as the test for patent eligibility threatens to undermine invention incentives, hamper patent prosecution, and greatly complicate patent litigation. While recognizing that the problems posed by patents on software and other computer-implemented inventions are real, this brief contends that patent eligibility doctrines beyond requiring specific application and categorical exclusion of business methods and other non-technological processes are poorly suited to address those concerns. It therefore concludes that the Supreme Court should turn away from the Funk Brothers/Flook/Mayo paradigm, and instead focus on elucidating the statutory requirements of patentability. By clarifying the constitutional and jurisprudential foundation for subject matter exclusions, the Court can promote legislative and administrative solutions that more directly address the evolving needs of the patent system.