On Thursday, more than three dozen prominent gun-control groups accused the Justice Department of “retraumatizing” survivors of the 2017 Sutherland Springs, Texas, mass shooting by appealing a lawsuit that found the US Air Force partially responsible for the attack.

A federal district judge ruled last year that the government was “60 percent liable” for the attack because, among other things, it failed to submit records that should have prevented the shooter from purchasing guns. A few months later, the judge ordered the government to pay more than $230 million in damages to the victims. However, the Justice Department appealed the decision, leaving survivors struggling to pay expensive, ongoing medical bills.

The organizations said it was “well past time” for the government to take responsibility for its “failures” and “lethal inaction” that led to the deadly 2017 shooting in a letter signed by Brady, March for Our Lives, and Everytown for Gun Safety. In November 2017, former airman Devin Kelley opened fire inside the First Baptist Church of Sutherland Springs with an AR-15-style rifle, killing 26 people and injuring 20 more. Kelley committed suicide after the attack.

The groups argued that the ongoing legal battle would jeopardize the “integrity” of existing gun laws, including the nation’s background check system, and would delay justice for a community that has suffered “irreparable trauma.”

A DOJ official confirmed that the parties are in mediation in the letter.

During the trial, Justice Department attorneys contended that the Sutherland Springs gunman’s violence was “unforeseeable,” and that background checks would not have prevented the massacre. This legal position contradicts the Biden administration’s efforts to increase background checks as a deterrent to such mass shootings.

Dozens of victims sued the US Air Force in 2018 after the branch claimed it failed to report Kelley’s history of violence, including a 2012 domestic assault conviction, to the FBI. That conviction, which resulted in Kelley’s dismissal from the Air Force, should have barred the former airman from purchasing the weapons used in the attack.

U.S. District Judge Xavier Rodriguez later found the Air Force to be 60% liable for the shooting, citing other details uncovered in the case, such as the fact that Air Force officials were aware Kelley had previously researched and threatened a mass shooting, as well as a history of severe mental health issues, which led officials to declare him “dangerous” and “a threat.”

According to testimony and evidence in the case, Air Force officials were so concerned about Kelley’s threats of violence that he was permanently barred from not only the New Mexico air base where he served, but all bases across the country.

Rodriguez ordered the government to pay more than $230 million to 84 victims and survivors in February. However, the Justice Department announced in June that it intended to appeal that judgment, further delaying any final outcome in the case.

The appeal, according to those involved in the case, has added to the anguish of survivors, who are struggling to pay expensive medical bills related to their debilitating physical injuries and lingering emotional trauma.

Attorneys for the Justice Department’s civil division, which is handling the case, have yet to reveal the grounds for their appeal. Opponents, however, have seized on their court declarations that background checks would not have stopped the violence.

Even as this case was being appealed, the Justice Department reached a settlement with other victims of mass shootings over background check errors. The Justice Department agreed last October to pay $88 million to the families of nine people killed in the 2015 shooting at Emanuel AME Church in Charleston, South Carolina, to settle claims that background check errors allowed the gunman to purchase a weapon. After weeks of negotiations, the government agreed to pay $127.5 million to the families of those killed in the 2018 shooting at Marjory Stoneman Douglas High School in Parkland, Fla., over allegations that the FBI failed to act on tips about the gunman. Both cases were settled prior to going to trial.

Groups representing families and survivors from Parkland, Newtown, Conn., and other prominent mass shootings over the past decade were among those who signed Thursday’s letter in support of the Sutherland Springs survivors — which mentions those other settled lawsuits.