In a patent infringement case involving two patents that concerned the use of thiopurine drugs to treat autoimmune diseases, the Federal Circuit's judgment finding infringement is reversed, where the patent processes--embodying researchers' findings that identify correlations between metabolite levels in the bloodstream and likely harm or ineffectiveness of thiopurine drugs with precision--were not patent eligible, since they were based on laws of nature and did not have additional features that provided practical assurance that they were genuine applications of those laws rather than drafting efforts designed to monopolize the correlations.