If women with a family history of breast or ovarian cancer want to check for mutations of their BRCA1 and BRCA2 genes, which can help predict the likelihood of the diseases, they have exactly one option: undergo a blood test created by Myriad Genetics. That’s because Myriad holds a series of patents relating to both genes, protecting its intellectual property and restricting other laboratories from performing the test. But in March, a federal judge ruled in favor of plaintiffs who argued that genes shouldn’t be patented—a decision that could affect the holders of thousands of gene patents issued since 1982.

According to the Patent Act, only a “new and useful process, machine, manufacture, or composition of matter” is worthy of a patent. After the U.S. Supreme Court ruled that a modified bacterium was patentable in 1980, the U.S. Patent and Trademark Office interpreted this rule broadly, allowing genes, removed and isolated from the body, to be patented.

That’s illogical, contends Mary Steele Williams, chief operating officer of the Association for Molecular Pathology, which is one of the case’s 20 plaintiffs represented by the American Civil Liberties Union and the Public Patent Foundation. “DNA sequences are discovered, not invented,” she says. “Removing DNA from the body and cleaning it up a bit doesn’t make it novel.”

This misinterpretation of the law, contends ACLU attorney Chris Hansen, is suppressing scientific research. “Say that a disease is influenced by five or more genes, each owned by someone different,” he notes. “Inevitably that type of situation will stifle clinical innovation.”

Moreover, he and the plaintiffs argue that Myriad’s monopoly on testing BRCA1 and BRCA2 ill serves patients faced with complex health decisions. If mutations are found, a patient is usually advised to undergo an elective mastectomy, even if no signs of the cancer are yet present. Many physicians would likely continue to use Myriad’s test even if its patents are invalidated, but the field would be open to competition, allowing for the development of other tests that could provide second opinions and force competitive pricing.

Myriad counters that gene patents fall well within the confines of patent law. “If we do not isolate the DNA, we can’t do our analysis,” says Richard Marsh, counsel for Myriad. “Patents benefit innovation. In exchange for getting a patent, you must disclose all the information about the invention to the public. And that allows people to make improvements and enlighten the general public.” As proof of both points, he cites the thousands of BRCA-related studies (conducted because Myriad either didn’t enforce the patent or granted scientists permission) that have been published in the years since Myriad claimed the patent. He also says that Myriad’s pricing is competitive with that of other genetic diagnostics and that second opinions are available to individuals through licensed providers who can check genetic sites of interest identified by the Myriad test.

Myriad, whose BRCA1 and BRCA2 patents begin to expire in 2014 and 2015, respectively, has filed an appeal, and arguments will be heard next year. “This is a landmark case along a road we’re just beginning to travel,” says Daniel Vorhaus, an attorney and editor of the Genomics Law Report. “And what’s great is that it has drawn a number of different voices into the conversation.