PHILADELPHIA (CBS) — Philadelphia has joined New York and San Francisco in suing the United States Department of Defense. The suit hopes to force the department to do a better job of reporting the criminal history of service members seeking to buy guns.

The U.S. Air Force convicted Devin Kelley of domestic violence in 2012 but never reported it to the National Instant Criminal Background Check System, or NICS, making it possible for him to purchase the guns with which he slaughtered 26 people at a Texas church.

Litigation chief Marcel Pratt of the Philadelphia Law Department says, “That caused us to take a closer look at it.”

He says the city depends on NICS when issuing gun permits.

“So, if the Department of Defense is not reporting military convictions into that database, it’s hard for us to trust our permitting process,” he said.

Pratt says the department is aware of the problem, but has done nothing to fix it so the cities are seeking a court order for a compliance plan.

“That will adequately insure that these failures of reporting don’t happen in the future,” he said.