(Reuters) - The U.S. Air Force’s failure to report the criminal record of Devin Kelley, the man who shot dead 26 people and wounded 20 more at a Texas church, could expose the service to liability, legal experts said.

Lorenzo Flores (L) and Terrie Smith react at a line of crosses in remembrance of those killed in the shooting at the First Baptist Church of Sutherland Springs, Texas, U.S., November 9, 2017. REUTERS/Rick Wilking

Kelley was convicted five years ago of assaulting his then-wife and child while he was in the Air Force, offences that made it illegal for him to possess a firearm.

The Air Force said on Monday it did not enter that information into a federal database used in background checks for firearms purchases, something it was legally required to do.

Government officials and agencies are often immune to civil lawsuits on the grounds that they need to be able to make policy decisions without fear of liability, but several lawyers said that immunity would not apply to the Air Force’s failure to report Kelley.

“We believe we have a viable case against the Air Force,” said Houston attorney Hartley Hampton, who has been approached by the family of one victim of Sunday’s mass shooting. But he added that he was still researching the issue.

A spokeswoman for the Air Force declined to comment.

Suing the Air Force could provide an avenue of redress for victims of the shooting at the First Baptist Church in Sutherland Springs, Texas. Lawsuits arising from mass shootings typically face long odds, because federal law specifically shields makers of guns and ammunitions from liability and it is often hard to show what steps other parties might have taken to prevent the crime.

No lawsuits have yet been filed, though several lawyers said that was not unusual just days after a shooting.

Under the 1993 Brady Bill, the Air Force was required to report Kelley’s 2012 court-martial to the National Criminal Information Center database. That would have caused him to flunk the background checks he passed to legally purchase firearms on two occasions in 2016 and 2017.

Timothy Lytton, a law professor at Georgia State University, said the Air Force would not be able to claim immunity in a lawsuit arising from the Texas shooting because its failure to report Kelley’s criminal record was not an act that fell within the service’s discretion. Instead, the Air Force simply failed to meet a legal requirement.

Lytton said that immunity from lawsuits existed to protect officials and agencies when they uphold statutory obligations or make policy decisions, with many court disputes centering on whether a particular federal action can be treated as a policy choice. But neither situation applied to the Air Force’s failure to report Kelley, he said.

Yale Law School professor Peter Schuck agreed that immunity would not protect the Air Force if victims and their families sued over Kelley’s ability to purchase firearms.

“I think plaintiffs have a strong case that could prevail against potential challenges from the government,” Schuck said.

Injury lawsuits against the federal government are subject to the same damages calculations as those against private parties but they are exclusively resolved through bench trials, where a judge and not a jury decides.

Even without immunity for the Air Force, Gregory Sisk, a law professor at the St. Thomas School of Law in Minnesota, said the plaintiffs would still need to prove both that the Air Force was negligent and that its negligence caused the shooting.

The latter claim might prove difficult, said Sisk, as the defense could claim that, even if Kelley had failed a background check, he could still have committed his crime with illegally obtained instead of legally purchased guns.

But lawyers in Texas, in the meantime, are already looking at ways to hold the United States liable.

“There’s no question that the shooter would not have been able to buy the guns were it not for the negligence of the Air Force,” said Austin plaintiff’s lawyer Laurie Higginbotham.