Patents are the lifeblood of biotechnology, the force that motivates companies to develop innovative medical treatments and bring them to market. The trouble is that these patents must be enforced in a court system that isn’t set up to adjudicate highly technical matters—resulting in rulings that seem arbitrary or even scientifically suspect.

The U.S. Court of Appeals for the Federal Circuit last year invalidated a patent held by the biotechnology firm Sequenom for a new technique in prenatal testing. The company had years earlier discovered the presence of fetal DNA in once-discarded maternal blood plasma. Testing that DNA would allow a doctor to diagnose such things as Down syndrome in utero, using only the mother’s blood instead of an invasive procedure.

Sequenom secured a patent, and when another firm began duplicating the technique, the company sued. But the court ruled that while “Sequenom’s invention is truly meritorious,” it would cancel the patent because the technique for testing the DNA was already “well-understood, conventional and routine.”

In July a different panel of the same court ruled onIn Vitro v. Cellzdirect, upholding a patent for refreezing certain liver cells used in research. The court acknowledged that the “individual steps of freezing and thawing were well known” but said that “repeating those steps was itself far from routine and conventional.”

The decisions in these two cases seem diametrically opposed. Yet the Supreme Court, which refused to consider Sequenom’s appeal during its most recent term, has yet to clear up the confusion.