This week, the Supreme Court held arguments in an unusual case: whether a company named Myriad can patent a piece of DNA. The company says it spent $500 million and 17 years studying a pair of genes called BRCA1 and BRCA2 that indicate an increased risk of breast and ovarian cancer. After half a billion dollars in investment, Myriad wants to own the genes — both its current process of testing for them, and any other tests that might isolate the same gene. For the past three years, Myriad has been defending those patents in court, culminating in this week's arguments before the highest court in the country.

"Life's instructions ought not be controlled by legal monopolies."

The problem is, the law won’t let you patent something if it’s a "product of nature." To most observers, that describes DNA pretty well. In arguments, justices joked about patenting the kidney, or atomic energy, but even they didn't reach the most ambitious levels of metaphor. No less than James D. Watson, official co-discoverer of DNA, found himself telling the court, "Life's instructions ought not be controlled by legal monopolies." It's a familiar line of argument; as Jonas Salk famously said about patenting the polio vaccine, "Could you patent the sun?"

But after the final arguments have been made, the justices, far from dismissive of the right to patent genes, were skeptical and cautious. If the predictions of court-watchers hold, the final ruling is likely to fall short of the sweeping condemnation many observers were hoping for, leaving many avenues for gene patents still open. One possibility suggested by the Justice Department is to limit the patents to cDNA, an edited version of the DNA that’s injected into a cell to produce a specific protein. That would provide some incentive for the first person to isolate a gene, but leave any given sequence of DNA open for research. But it dodges the larger question: how did the building block of life become so easily bought and sold?

Mapping a person's whole genome is still too error-prone and expensive

The idea of genetic patents grows directly out of the way most human genome research is conducted. Despite the falling price of sequencing, it still costs thousands of dollars to sequence an entire genome. As a result, mapping a person's whole genome is too expensive and error-prone to work in most clinical settings. Instead, labs chop up chromosomes and look for unique strings of nucleotide that they can isolate and study. If the studies turn up something useful, researchers can easily test patient DNA for the same string, effectively divorced from the rest of the genome. In many cases, the patent-holders don't even know where on the chromosome the patented gene is. They don't need to. As long as they've got a workable test, they can build studies around it, and build a meaningful tool for doctors and patients from there.

To a CEO, this process looks like something you should patent. After investing lots of time and money, researchers created something (in this case, a medical test) that has real value for patients, value that was shored up by arduous and extensive testing. If it were a special kind of X-ray that told patients about their risk of breast cancer, the case would be open and shut. But because genes are involved, drawing the line gets complicated fast.

The expensive and difficult work is isolating the gene itself. In exchange for that, companies want a patent

The simple answer — and one the ACLU has suggested many times in pressing the case — is just to patent the test, but for many companies, that's not enough. The test itself is nothing special. It would be too easy for a rival company to circumvent the patent by developing an alternate test for the same string of nucleotides. As the field develops, new sequencing methods are bound to develop, and researchers want a patent that can survive the next generation of testing technology. The expensive and difficult work is isolating the gene itself, and doing the clinical tests that establish its meaning. In exchange for that work, companies like Myriad want the protection of a patent.

As the BRCA genes became more important, Myriad decided to break the truce

Traditionally, they've gotten it. Patents have been granted on genes for decades. The first official DNA patent came in 1982, when a trio of University of California scientists isolated the cDNA strand to produce human growth hormone. The university, eager for profit, licensed it to biotech companies like Lilly and Genentech for a new generation of HGH treatments. For the most part, patent-holders taken care to stay on the right side of the research community, offering free licenses and not enforcing most of the rights associated with their patents. Since most of the research was in such an early stage, this was a cheap concession. But as the BRCA genes became increasingly important in preventative breast cancer testing, Myriad decided to break the truce. It started aggressively enforcing the BRCA patents, serving violation notices to labs that performed infringing tests. Labs still performed the test (it was too effective to ignore), but they had to license it from Myriad, which made the test more expensive and less common. Even worse, anyone who wanted to research the gene had to get Myriad’s approval, which throttled the usual flow of research.

If it sounds bad in broad strokes, the specifics are even worse. In one case that the ACLU has aggressively pushed, a woman received a negative result from Myriad’s BRCA test only to discover, years later, that she had a BRCA mutation that Myriad hadn’t studied. Since Myriad didn’t study it, no one could, and there was no effective test for her unique mutation. In the meantime, a relative’s ovarian cancer advanced to the point of being inoperable, with no evidence that she was genetically at-risk. Would a patent-free system have inspired the research that would have saved her life? The woman certainly thinks so, and her case, among others, has spurred medical associations into a full fledged legal battle. The American Medical Association and AARP have already sided against Myriad, and dozens of smaller medical groups have signed on in their wake.

41 percent of identified genes fall under some patent

And while Myriad is the most visible case, they're not the only bad actor. Below the radar, you'll find a host of companies that exist mostly to accumulate and license patents, often offering no more than a connection to an established protein. 41 percent of identified genes fall under some patent or another, which presents a growing problem for genetics research. The new wave of personal genomics companies like 23andme fall into an even stranger place, using open tests to entice customers, but potentially generating revenue from their own portfolio of patents. Depending on how the court rules, they could end up either facing a dwindling supply of open-source genes, or having to rewrite their business model entirely.

In the end, 30 years worth of gene patents is a lot to overturn, and while the justices seem skeptical of the genetic patent system, they also seem wary of too large an overhaul — especially one that might stunt investment in the growing biotech field. But it's hard to predict what will become restrictive as the field develops, or how the Supreme Court will parse the science of the case. The Court is expected to issue its decision in late June; until then, all Myriad and others can do is wait.