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Many pharmacies across the nation are sold out of Covid-19 rapid diagnostic tests, making it exceedingly difficult for Americans to contain the spread of the Omicron variant of SARS-CoV-2, the virus that causes Covid-19. Similar shortages and backlogs hampered efforts to control earlier surges, too.

The lack of diagnostic tests has been blamed on everything from slow FDA approval of rapid tests to manufacturers deliberately restricting supplies to keep prices high. But there’s another culprit — the U.S. Supreme Court.


In a 2012 case known as Mayo v. Prometheus, the court effectively blocked patent protections for diagnostic tests and procedures. Its decision was a legal bombshell that upended the prior law on patent eligibility. And it has had disastrous real-world consequences for Americans.

Fortunately, Congress is now considering bipartisan legislation to restore much-needed patent protections for diagnostics. That could help accelerate the development of tests, not just for Covid-19 but also for heart disease, stroke, various types of cancer, and many other health threats that need early and accurate detection.

Developing new diagnostic tests and methods is slow and expensive work. Without patent protections, there are rarely sufficient incentives for investors or companies to commit the necessary funds to bring new potentially lifesaving tests to market.


In the wake of the Mayo decision, work on diagnostics dropped sharply. Many small biotech companies that were trying to develop new diagnostics went out of business, while those that survived could barely continue their research. Institutions like the renowned Cleveland Clinic gave up on programs that were designed to find new diagnostic methods after their patents evaporated under the Mayo ruling.

All told, venture capital investments in diagnostic technologies were $9.3 billion lower in the four years following the ruling than they otherwise would have been, according to a forthcoming analysis by A. Sasha Hoyt in the Washington and Lee Law Review.

These disastrous consequences are particularly galling because the Supreme Court’s reasoning in Mayo was downright bizarre.

The case revolved around a diagnostic test developed by Prometheus Laboratories that measured how well people were metabolizing certain medicines to treat autoimmune diseases. Different people metabolize the same dosage at different rates, which posed a problem. Slow metabolizers, with too much of the drug in circulation, could experience dangerous side effects like pancreatitis that can result in severe pain and hospitalization. Fast metabolizers, with too little of the drug in circulation, receive little or no relief from the drug for their autoimmune conditions.

The Prometheus test gave doctors a way to keep patients healthy by accurately gauging what level of metabolite indicated too high a dose and what level indicated too small a dose, making it possible for doctors to titrate the dosage for each patient.

For years, Mayo Collaborative Services, a for-profit diagnostics lab affiliated with the Mayo Clinic, used the Prometheus test. Then, in 2004, Mayo began using its own test, which was based closely on the design of the Prometheus test. Prometheus sued for patent infringement, and the case ultimately wound its way to the nation’s highest court.

The Supreme Court justices decided that the test merely clarified the optimal levels of metabolite in each patient. And since metabolization is a “natural phenomenon,” which have long been ineligible to be patented, they decided the Prometheus test was not eligible for patent protection.

The court’s ruling discounted its own precedent in 1981, in Diamond v. Diehr, which would have required the justices to consider how the Prometheus patent required — and in fact specified in detail — human interventions with patients such as administering a drug and monitoring several chemical reactions that resulted from metabolizing the drug and then testing patients’ blood for the amount of certain metabolites.

In other words, Prometheus hadn’t sought to patent a natural phenomenon like metabolization. It patented a method to understand the effects of a natural phenomenon — a method that was essential to properly dosing and treating patients.

The deleterious real-world impact of the decision on the diagnostics industry is far worse than the flaws in the Supreme Court’s analysis. As Kimberly Moore, chief judge of the U.S. Court of Appeals for the Federal Circuit, noted, “since Mayo, [lower courts] have held every single diagnostic claim in every case before us ineligible” due to the Supreme Court’s binding, but arguably erroneous, reasoning.

And despite such complaints from lower courts, the Supreme Court has rejected dozens of requests to reconsider the precedent-reversing, patient-harming Mayo ruling over the past decade.

Congress is now looking to overturn the Mayo decision by passing bipartisan legislation to explicitly restore eligibility to diagnostic tests and methods — a reform that would revive the diagnostics industry and advance Americans’ health. A bipartisan team of senators, led by Chris Coons (D-Del.) and Thom Tillis (R-N.C.), and supported by Mazie Hirono (D-Hawaii) and Tom Cotton (R-Ark.), are spearheading this effort.

For a healthier America, I hope they soon succeed.

Paul R. Michel served on the United States Court of Appeals for the Federal Circuit from 1988 to his retirement in 2010, and as its chief judge from 2004 to 2010.

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