A retired Georgia Tech professor won't have to pay $584,000 in attorney fees to Lyft Inc. over his unsuccessful patent infringement suit.

U.S. District Judge Jon Tigar ruled that, although Stephen Dickerson's RideApp Inc. and his attorneys at Kasowitz Benson Torres engaged in some "questionable" litigation conduct, it didn't rise to the "egregious" level that would trigger fee shifting under Section 285 of the Patent Act.

Lyft had complained that RideApp forged ahead with its suit after the Patent Trial and Appeal Board found the patent claims indefinite in July 2019. Then RideApp changed its claim construction positions at the last minute before Tigar. Lyft was seeking fees only from July forward.

"While the Court ultimately found the PTAB's analysis persuasive," Tigar wrote in a three-page order Monday, "it does not find exceptional RideApp's decision to continue this litigation following the PTAB's non-dispositive ruling."

RideApp originally sued Lyft in New York federal court in 2018, saying that Dickerson had patented the idea for Lyft and Uber's ride-hailing platform in the early 2000s. Kasowitz Benson Torres partner Marc Kasowitz alleged that Lyft had "egregiously infringed the '730 patent without paying any compensation to Prof. Dickerson, despite earning up to $1 billion in annual revenue." The company was seeking more than $500 million in damages, according to Lyft.

Lyft got the case transferred to San Francisco. Both Lyft and Unified Patents then asked the U.S. Patent and Trademark Office's PTAB to review the validity of Dickerson's patent. The PTAB issued orders in July and August declining, each time stating it could not determine validity because the patent claims are indefinite.

Tigar ruled in October that he agreed the claims are indefinite. "In this case, the '730 patent contains no algorithm whatsoever—simple or otherwise—describing how the invention performs the tracking function," he wrote.

He also dinged RideApp for belatedly changing its proposed claim construction, saying its conduct was "not conducive to the orderly progress of this case."

Lyft then moved for fees. RideApp had argued that the PTAB rulings weren't binding and noted that the U.S. Court of Appeals for the Federal Circuit recently ruled that the PTAB judges aren't constitutionally appointed. RideApp said a fee award could wipe it out, leaving it with no money to pursue an appeal of Tigar's order.

Tigar wrote Monday that he would not lightly depart from the American rule of each side paying its own fees. The PTAB's ruling was not controlling, and patents remain presumptively valid, he added.

"RideApp's conduct, although 'questionable,' does not, in this Court's view, rise to the level required to render the case exceptional under Section 285," he concluded in a three-page order.

A Kasowitz team featuring partner Jeffrey Toney represented RideApp in the fee litigation. Lyft is represented by Baker Botts.

RideApp dismissed a similar case against Uber in Georgia without prejudice last November, with the proviso that it may refile if it wins its appeal of Tigar's claim construction.