Critics of human gene patents rejoiced last month when the nation's highest court ruled that human genes can't be patented. A company called Myriad Genetics claimed to own genes called BRCA1 and BRCA2 whose mutations are associated with an elevated risk of breast cancer. But the Supreme Court ruled that no one could own humanity's genetic code.

Believing that the ruling opened the market for competing breast-cancer tests, several companies introduced BRCA testing products. But this week Myriad, whose gene patents had given it a de facto monopoly on BRCA tests, began suing them. Myriad says that even after its Supreme Court setback, it still has patents covering its competitors' products.

If these lawsuits succeed, they could transform last month's Supreme Court ruling into little more than a symbolic gesture. While the claims at issue in Myriad's new lawsuit do not literally claim human genes, they are broad enough to effectively block anyone else from offering BRCA tests.

The patent claims the Supreme Court invalidated last month were "composition of matter" claims, covering the chemical structure of the BRCA genes. But Myriad's patents also have "method" claims covering processes for diagnosing breast cancer. And while these patents use different language than the composition-of-matter patents the high court invalidated, their practical effect on the genetic testing market could be very similar.

Consider Patent 6,951,721, one of the patents cited by Myriad in its lawsuit against competitor Ambry Genetics. It claims the concept of diagnosing breast cancer by "determining the nucleotide sequence of the BRCA1 gene" from a "female individual" and then checking for mutations at specific points on the gene. The patent isn't limited to any particular technology for isolating or sequencing the patient's BRCA1 gene. So while it's not technically a patent on the BRCA1 gene, it might as well be.

Another patent claims the concept of diagnosing a predisposition to breast cancer by looking for mutations in the BRCA2 gene. The patent lists more than a dozen conventional techniques for determining the sequence of a patient's BRCA2 gene and claims ownership of all of them.

Myriad cites eight other patents in its lawsuit against Ambry. While most are not as broad as these two, all follow the same pattern: claiming the use of standard diagnostic techniques to sequence a patient's BRCA genes and check whether they've mutated. While these aren't technically patents on the BRCA genes themselves, it's hard to see much practical difference between claiming ownership of a gene and claiming ownership of the concept of testing whether a patient's gene has mutated using conventional laboratory techniques.

And that places the patents in tension with the Supreme Court's precedents. For example, in the 2012 case of Mayo v. Prometheus, the high court rejected a patent on a strategy for adjusting the dosage of a drug to treat autoimmune diseases. The patent claimed the concept of observing the concentration of a particular chemical in the patient's blood and using that measurement to adjust the drug dosage. The patent wasn't limited to any specific method of measuring the patient's blood.

While the patent was framed as covering a method — measuring the patient's blood and adjusting the drug dosage accordingly — the high court found that the patent was really an attempt to claim a fact about how the human body reacts to autoimmune drugs. The court noted that the patent merely instructed doctors to "engage in well-understood, routine, conventional activity" to determine blood chemistry. The only new element of the patent was the observation that particular levels of blood chemicals signaled a need for higher or lower drug dosage. That's a scientific fact that isn't eligible for patent protection on its own, and adding conventional diagnostic steps doesn't transform it into a patentable invention.

A similar point seems to apply to Myriad's patents. Although several of them are framed as methods for diagnosing breast cancer, these methods appear to involve "routine, conventional activity" for determining the sequence of the patient's BRCA genes. As with the Prometheus patent, the only innovative element of the patents seems to be a fact about the human body: that the BRCA gene mutations are associated with breast cancer. But the Supreme Court said in June that this fact wasn't eligible for patent protection. And combining that unpatentable scientific discovery with conventional diagnostic steps may not be enough to produce a patentable invention.

In the run-up to the Supreme Court's Myriad ruling last month, patient advocates described how Myriad's de facto monopoly on BRCA testing had undermined patient choice and reduced the quality of genetic testing. Myriad lost the theoretical argument over whether human genes could be patented. But if the courts want that ruling to have practical significance, they will need to take a hard look at Myriad's other patents, which are gene patents in all but name.