On Tuesday, March 20, 2012, the U.S. Supreme Court issued its decision in Mayo Collaborative Services v. Prometheus Laboratories, Inc. 566 U.S. ____ (2012). In a unanimous decision, the Supreme Court sided with Mayo and held that method claims involving administering a drug to a patient and determining the effect were not patentable subject matter. The court concluded that the method was directed to a “law of nature” and therefore not patentable. The court reasoned that the Prometheus patent added nothing of significance to the natural correlation between drug dosages and drug metabolite levels and that the patent otherwise had the effect of stifling future innovation in this area. The implications of this case are significant for certain segments of the pharma and biotech industries, particularly those wishing to obtain or enforce patents with certain types of diagnostic claims.