Daralyn Durie, Durie Tangri. Photo: Jason Doiy/The Recorder

The latest patent battle battle between Illumina Inc. and Ariosa Diagnostics Inc. over Ariosa’s Harmony prenatal test ended quicker than the first.

U.S. District Judge Susan Illston on Monday ruled that two new patents asserted by Illumina are directed to natural phenomena and are ineligible for patent protection under Section 101. Her 14-page order snuffs out a suit that Illumina filed in May, just a few months after winning a $27 million jury verdict against Ariosa based on older patents.

That case spanned six years, and both sides are appealing the outcome to the U.S. Court of Appeals for the Federal Circuit.

Monday’s ruling hands a win to Daralyn Durie of Durie Tangri, a newcomer to the feud.

Illumina and Ariosa, which is owned by Roche Molecular Systems Inc., are rivals in the burgeoning noninvasive prenatal test industry. The tests screen for genetic disorders using a mother’s blood sample, reducing the need for riskier procedures like amniocentesis.

Illumina sued Ariosa in May, asserting two patents on a method for enriching cell-free fetal DNA that circulates in maternal plasma. A few years ago, Illumina researchers made what they describe as a surprising discovery that advances the science. They found that fetal DNA fragments are smaller than maternal DNA fragments, and that test results can be improved if fragments greater than 300 base pairs are isolated and removed from the blood sample.

Ariosa has been represented by Irell & Manella, but this time around turned to Durie Tangri. Durie argued that Illumina’s 9,580,751 and 9,738.931 patents are directed to nothing more than the observation and analysis of natural phenomena.

On Monday, Illston agreed. “Changing the ratio of two natural products in a mixture and analyzing one of those products does not impact whether an invention is directed towards a natural phenomenon,” she wrote.

Durie said Thursday that a key to the win was raising the argument in an early summary judgment motion, rather than on the pleadings. “We wanted Judge Illston to be confident that she had a complete factual record,” Durie said.

Illumina, which was represented by Weil, Gotshal & Manges partner Edward Reines, took depositions but elected not to submit an expert witness declaration, Durie said.

Reines had argued in his opposition that the U.S. Patent and Trademark Office carefully weighed the eligibility issue in light of a leading Federal Circuit decision on natural phenomena before issuing the patents. The inventors claimed a specific process “in their own inventive way with discrete laboratory steps, including DNA extraction, size separation, removal of DNA above a certain size, and analysis of the resulting DNA fraction,” Reines argued.