Federal Circuit Judge Kara Stoll

The U.S. Court of Appeals for the Federal Circuit has revived a long-running patent infringement fight between providers of ambulatory cardiac monitoring systems. Along the way it's opened a new front in the ongoing debate over how to properly analyze Section 101 defenses.

The court found that a CardioNet Inc. patent on an automated process for identifying atrial fibrillation and flutter, and distinguishing them from more benign forms of cardiac arrhythmia, is eligible for patent protection.

"In our view, the claims 'focus on a specific means or method that improves' cardiac monitoring technology; they are not 'directed to a result or effect that itself is the abstract idea and merely invoke generic processes and machinery,'" Judge Kara Stoll wrote for the majority in CardioNet v. InfoBionic.

It's a much-needed win for CardioNet, now known as BioTelemtry Inc., and Sidley Austin, which had struck out before District Judge Indira Talwani of the U.S. District Court of Massachusetts and the Patent Trial and Appeal Board on several other patents. As for the patent before the Federal Circuit on Friday, Talwani had found it directed to the abstract idea of collecting and analyzing information, albeit potentially life-saving information.

CardioNet had argued that its claim specification explains that the invention achieves more accurate and clinically significant detection of atrial fibrillation and atrial flutter. But Talwani ruled that CardioNet had failed to identify improvements to any particularized computer technology.

On appeal, the parties disputed whether a district judge ought to consider prior art in making such a determination. Stoll said no. When considering patent eligibility on the pleadings, the court may consult the plain claim language, written description and prosecution history. But "the court need not consult the prior art to see if, in fact, the assertions of improvement in the patent's written description are true."

Judge S. Jay Plager concurred.

That provoked a dissent from Judge Timothy Dyk, even though he agreed with Stoll that the CardioNet patent should be eligible. "The Supreme Court and our cases have consistently held that whether a practice is 'longstanding' or 'long prevalent' is central to the step one inquiry and have never suggested that prior art is irrelevant to that question," Dyk wrote.

Stoll replied that a district judge can take judicial notice of a longstanding practice if there's no evidence of such practice in the intrinsic record. "But there is no basis for requiring, as a matter of law, consideration of the prior art in the step one analysis in every case," she wrote.

Sidley partner Ching-Lee Fukuda had the winning argument for CardioNet. Also on the briefs were Sidley partner Jim Badke, counsel Todd Simpson and associate Nathan Greenblatt.

InfoBionic was represented by Latham & Watkins.