The Federal Circuit’s decision below directly conflicts with this Court’s patentable subject matter precedent by upholding patent claims to routine, conventional applications of a law of nature. If allowed to stand, the decision will eviscerate this Court’s unanimous and repeated determinations that such claims lack the “inventive concept” that is required of patentable subject matter. Alice Corp. Pty. Ltd. v. CLS Bank Int’l., 573 U.S. 208, 217 (2014); Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66, 72 (2012). The divided Federal Circuit panel held the claims at issue here were not “directed to” a law of nature because they claim a “specific method of treatment.” Pet. App. 35a. This interpretation of the term “directed to” is incompatible with the Court’s usage in Alice, 573 U.S. 208. It is also directly at odds with the Court’s invalidation of the method-of-treatment claims at issue in Mayo, 566 U.S. 66, on patentable subject matter grounds. The Mayo decision reaffirmed the principle that patentability requires more than simply directing a practitioner to apply an otherwise ineligible natural law in a “routine, conventional” way. 566 U.S. at 73. The panel in this case sought to distinguish Mayo on the grounds that the patent at issue explicitly recites the step of adjusting a drug dose in applying a natural law, whereas the dose adjustment was merely implicit in the claims invalidated in Mayo. This distinction is untenable, as it depends on the “draftsman’s art,” Alice, 573 U.S. at 224, and ignores this Court’s repeated ruling that mere specificity is not sufficient to transform a natural law into patent eligible subject matter. Mayo, 566 U.S. at 88-89 (citing Parker v. Flook, 437 U.S. 584 (1978)). The Federal Circuit is obligated to follow this Court’s guidance by elaborating the limits on 35 U.S.C. § 101 patent eligible subject matter in a manner that conforms with the legal interpretation and rationale set out in this Court’s precedents. The decision below shirks that duty. This Court has adopted a two-step framework for analyzing patentable subject matter in order to ensure that patents are awarded only to claims that add an “inventive concept” to the underlying natural law. The Federal Circuit majority’s interpretation of this analysis would render this framework toothless because no method of treatment applying a discovered law of nature would ever be considered “directed to” that law of nature, regardless of whether the claim adds only “well-understood, routine, conventional activity” to the otherwise-ineligible subject matter. Mayo, 566 U.S. at 73. The harmful consequences of this decision are real and immediate. The U.S. Patent and Trademark Office (USPTO) has issued guidance that explicitly adopts the reasoning of the majority’s holding and instructs examiners that “method of treatment” claims that apply natural relationships should be considered per se eligible subject matter so long as integrated into a practical application — such as a treatment claim — even if that application is uncreative, routine, or conventional, once the ineligible discovery has been made. This guidance, like the decision below, ignores the standards of § 101 articulated by this Court for patentable subject matter in general and for medical treatment patents in particular. Moreover, the reasoning of the decision below need not apply only to medical treatment patents. It is thus likely that the decision’s erroneous interpretation of “directed to” will be extended to other classes of patents, enabling clever patent drafters to avoid the critical second step of this Court’s patent eligible subject matter analysis. The decision below is exceptionally important. The Federal Circuit’s and USPTO’s disregard of Mayo and Alice are unmistakable and growing. Review and correction by this Court are vital now, before the harmful effects of the decision and its implementation by the USPTO become widespread. Only immediate review will prevent thousands of ineligible patents from being improperly issued and improperly upheld in the courts below and remaining in effect until some potential future opportunity for this Court to consider and invalidate them. Left uncorrected, the Federal Circuit’s decision and the USPTO guidance based on it will allow the piecemeal appropriation of the public domain. Patent law carefully limits the subject matter of patents to ensure the existence of a robust and unrestricted public domain for routine and conventional uses of the laws of nature, even if those laws are newly discovered. Patents must not be allowed to monopolize the basic ideas and natural laws that provide the foundation for medical innovation, research and treatment. If they do, downstream innovation will be hampered or blocked and vital medical practices and decisions will face undue interference.