The retired Georgia Tech professor who says he patented the idea of ride-sharing-by-cellphone 19 years ago got a mixed bag of news from the Patent Trial and Appeal Board last week.

The PTAB declined to review the validity of Stephen Dickerson's patent in a challenge filed by Unified Patents. That means RideApp will probably get its day in court against Lyft in San Francisco and against Uber Technologies in Georgia.

The rest of the news was decidedly bad. That's because the reason the PTAB judges rejected Unified's challenge is that they found the challenged patent claims indefinite.

The patent describes “a wireless means of on-demand allocation of a passenger to a specific vehicle through [a] central data system.” The board found that the claim specification doesn't explain how passenger “allocation” is performed. RideApp pointed to a few flowcharts, but the board found they weren't satisfactory.

The PTAB is not empowered in inter partes review proceedings to invalidate claims for indefiniteness. And because the claims are indefinite, the board can't decide if they're anticipated or obvious. “We are unable to apply the claim language to the prior art,” Judge Jason Melvin wrote in his July 17 order. So the IPR is over.

RideApp is facing another IPR filed by Lyft in February. Assuming the board doesn't institute proceedings there either, the next hurdle facing RideApp will be a Section 101 motion that Lyft has filed in San Francisco and that also turns largely on the meaning of “allocation.”

If RideApp survives the patent eligibility challenge and makes it to claim construction and summary judgment, it will then face some serious explaining about indefiniteness, said Brent Babcock, a PTAB specialist at Womble Bond Dickinson who's not involved in the cases.

The PTAB's claim construction isn't binding on district judges, but it would behoove RideApp to provide a good faith explanation of how the board erred.

“You'd be getting out your microscope and looking over the specification real carefully to point out where the PTAB was wrong,” Babcock said.

“If it's just, 'That's just the board and their decision isn't binding on you, judge,'” that may not cut it, Babcock said, especially now that the PTAB and district courts are using the same claim construction standard.

Unified was represented by Haynes and Boone partners Raghav Bajaj, David McCombs and David O'Dell, plus by Unified in-house attorneys Jonathan Bowser and Ashraf Fawzy. RideApp was represented by Kasowitz Benson Torres senior counsel Ralph Gaskins. The Kasowitz firm also represents RideApp in San Francisco federal court. Kilpatrick Townsend & Stockton represents RideApp in Georgia federal court. Baker Botts represents Lyft at both the PTAB and in San Francisco federal court. No attorney has noticed an appearance yet for Uber in Georgia.