All nine justices on the U.S. Supreme Court today agreed to wipe out patents that told doctors how to tell how much of a drug to give a patient. The patents' sin? They did little more than describe a "law of nature".

Prometheus Labs held sole rights to a couple of patents. The patents dealt with testing patients with autoimmune diseases to find out whether a higher or lower dose of a drug would improve the drug's effect. Prometheus sold kits that let doctors give the tests, which measured how much "metabolites" patients produced after getting a dose of "a thiopurine compound". The Mayo Clinic bought the Prometheus tests for awhile but then quit and started using its own test.

Prometheus sued for patent infringement. It lost on summary judgment. The Federal Circuit reversed not once but twice — the first time before Bilski v. Kappos, 130 S. Ct. 3218 (2010), which deemed a hedging process an unpatentable "abstract concept", and the second time after the Supreme Court sent the case back to it for further review in light of Bilski.

The Federal Circuit's ruling did not impress the justices. They, speaking through Justice Breyer, thought that the patents didn't do enough with a law of nature — how a human body responds to a dose of a Drug A — to avoid granting a monopoly on the law of nature:

If a law of nature is not patentable, then neither is a process reciting a law of nature, unless that process has additional features that provide practical assurance that the process is more than a drafting effort designed to monopolize the law of nature itself. A patent, for example, could not simply recite a law of nature and then add the instruction "apply the law." Einstein, we assume, could not have patented his famous law by claiming a process consisting of simply telling linear accellerator operators to refer to the law to determine how much energy an amount of mass has produced (or vice versa). Nor could Archimedes have secured a patent for his famous principle of flotating by claiming a process consisting of simply telling boat builders to refer to that principle in order to determine whether an object will float.

Mayo Collaborative Services v. Prometheus Laboratories, Inc., No. 10-1150, slip op. 8-9 (U.S. Mar. 20, 2012).

See, e.g., "'Process' Must Do Stuff to Deserve a Patent, Federal Circuit Affirms"; "Bolts of Business Insight May Flash in Pan at Supreme Court; Bilski the Hedger"; "Supreme Court Ends Term: Guns, Prayers, Accounting, and Patents".