By Steven Seidenberg for Intellectual Property Watch

On 20 March, the US Supreme Court cut back on the types of inventions that can be patented in America. The court held in Mayo Collaborative Services v. Prometheus Labs., Inc. that one cannot patent an invention which merely applies known technology to natural phenomena.

The decision is here [pdf].

The unanimous decision overturns a medical treatment patent, which claimed a process for determining how much thiopurine medication a patient should receive in order to treat certain autoimmune diseases.

Writing for the court, Justice Stephen Breyer stated that this process was unpatentable because it claimed a monopoly on a law of nature – the relationship between the amount of thiopurine metabolites in a person and the likelihood that the thiopurine drug dosage is ineffective or harmful. Although some technological measures were needed to ascertain the amount of metabolites in a patient’s blood, these measures “were well known” by scientists and did not suffice to make the invention patentable.

The ruling is likely to a major impact on the medical and biotech industry. Many methods of medical diagnoses and medical treatment are now unpatentable. And the ruling may kill patents on human genes – including Myriad Genetics Inc.’s controversial patent on two breast cancer genes. The Federal Circuit (America’s so-called “patent court”) recently upheld Myriad’s patent [pdf], but that ruling is now in trouble, according to many experts.