Mayo Collaborative Services v. Prometheus Laboratories, Inc.
Headline: Court invalidates patents on medical diagnostic methods that merely apply natural drug‑metabolism correlations, making it harder for companies to patent simple tests and freeing doctors and researchers to use those correlations.
Holding: The Court held that the patented processes describing correlations between drug metabolites and treatment outcomes are not patentable because their additional steps are routine or conventional and do not meaningfully transform the natural laws.
- Makes patents on simple diagnostic correlations harder to obtain.
- Allows hospitals and researchers to use such medical correlations more freely.
- Requires more inventive steps to secure diagnostics patents.
Summary
Background
Prometheus Laboratories owned patents that described how levels of certain drug breakdown products in the blood (metabolites) relate to whether thiopurine drug doses would be too low, effective, or toxic. Mayo Clinic developed and planned to use its own test measuring similar metabolite levels. Prometheus sued Mayo for infringing patents that set out specific numerical metabolite thresholds and steps telling doctors to give the drug, measure metabolite levels, and consider the results.
Reasoning
The Court examined whether those patent claims did more than simply state natural correlations. It concluded the claims primarily recited a natural law — the link between metabolite levels and patient response — and that the added steps (give the drug, measure levels, use the numbers) were routine or conventional. The Court relied on earlier decisions showing that merely adding ordinary activities to a law of nature does not make it patentable, and it rejected the idea that other patent rules should replace this basic limit. The Court reversed the Federal Circuit and held the claims invalid.
Real world impact
The ruling means patent protection cannot depend only on discovering correlations between biological measurements and outcomes unless the claim adds something significantly more than standard testing or treatment steps. Companies and researchers working on diagnostic tests that primarily embody natural relationships will face higher hurdles to obtain patents, and doctors and labs may be freer to use such correlations without infringing the particular patents at issue. The Court left open that more inventive, specialized steps might still qualify for patent protection.
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