The Supreme Court has tossed out a medical patent for Prometheus Laboratories, a decision that could affect the burgeoning field of personalized medicine.
The justices on Tuesday unanimously agreed that the patent held by the company -- owned by Switzerland-based Nestle -- was invalid.
The patent covers a blood test that helps doctors determine the proper dosage for a drug, thiopurine, to treat autoimmune illnesses. The Minnesota-based Mayo Clinic had challenged the patent, which is keeping them from marketing its own test.
Courts have been fighting over whether the Prometheus test had patented a natural phenomenon, which cannot be patented.
The high court in an opinion written by Justice Stephen Breyer said the Prometheus blood test used "unpatentable" natural laws.