In the wake of last week's ruling striking down medical diagnostic patents, the Supreme Court has asked an appeals court to reconsider a year-old ruling allowing patents on human genes.

In the 1990s, a company called Myriad Genetics obtained patents related to two genes, known as BRCA1 and BRCA2, that are linked to breast cancer. They have used those patents to establish a monopoly on BRCA gene testing services.

Myriad's patents make several different claims related to the BRCA genes. The firm claims to own the "isolated" form of the genes themselves. They claim the concept of comparing a patient's DNA sequence to the known "normal" BRCA genes. And they claim the concept of testing a potential cancer cure by growing cells with healthy and mutated BRCA genes, respectively, applying a potential treatment, and observing whether the cultures' growth rates are affected differently by the treatment.

With the assistance of the ACLU and the Public Patent Foundation, a broad coalition of medical professionals filed suit, seeking to have these patents declared invalid. They prevailed at the trial court level. The court accepted the novel argument that it was the information content of a DNA sequence that mattered, and the process of performing genetic testing relied on the same information that's used by living organisms.

That ruling was partially overturned by the US Court of Appeals for the Federal Circuit. It held that the "isolated" form of the BRCA genes is sufficiently different from its natural state on a human chromosome to constitute an artificial—and therefore patentable—chemical compound. It also upheld the claims related to testing cancer treatments. However, the Federal Circuit rejected the patents that claimed the concept of diagnosing breast cancer based on mutations in a patient's BRCA genes.

The Federal Circuit's decision was appealed to the Supreme Court. Rather than accepting the case, the high court essentially assigned the Federal Circuit a do-over on Monday, ordering the appeals court to reconsider its decision in light of last week's ruling on medical diagnostic patents.

The decision to send the case back to the Federal Circuit does not create a binding precedents, and certainly does not, as the Associated Press suggests, mean that the patents themselves have been "thrown out" or "overturned." Rather, it simply means that the justices want to give the lower court a chance to consider whether last week's ruling on medical diagnostic patents affects the reasoning in the case. The Court of Appeals for the Federal Circuit may very well reach the same result.

The effects of last week's ruling on the case may be limited because the claims that were most similar to those the Supreme Court rejected last week—related to diagnosing a patient based on the state of her BRCA genes—had already been struck down by the appeals court. But the appeals court may take last week's unanimous ruling as a signal of greater Supreme Court skepticism of patents connected to natural processes, and may give the claims it upheld last time greater scrutiny.

Either way, it's a safe bet that whoever loses at the appellate level will appeal the case to the Supreme Court.

Listing image by Photograph by Daniel Weir