A federal judge in Texas ruled against a request by the families of those killed in two Boeing 737 MAX crashes to alter the terms of a 2021 deferred prosecution agreement (DPA) between the company and the Department of Justice (DOJ) to add an independent compliance monitor.

Judge Reed O’Connor of the U.S. District Court for the Northern District of Texas blocked the families’ demand to impose a compliance monitor on Boeing as part of its DPA, among other requests.

In a decision filed Thursday, Judge O’Connor said the court did not have the authority to add new conditions to the three-year DPA, under which Boeing agreed to pay more than $2.5 billion in penalties and compensation to victims. Boeing also agreed to remedial changes to the way it reviews potential safety issues in its aircraft.

“This court has immense sympathy for the victims and loved ones of those who died in the tragic plane crashes resulting from Boeing’s criminal conspiracy,” O’Connor wrote. “Had Congress vested this court with sweeping authority to ensure that justice is done in a case like this one, it would not hesitate.”

Paul Cassell, a professor and former federal judge who represented the families in the case, said they were “disappointed” and would appeal the decision to the Fifth Circuit Court of Appeals.

“Boeing and the DOJ crafted an illegal and secret plea deal without any chance for the families to confer about it, which is required by the Crime Victims’ Rights Act,” Cassell said in an emailed statement. “We are optimistic our appeal will vindicate the families’ rights in this case and ensure that never again are deals like this one reached secretly and without victim involvement.”

The families, who had previously been granted standing under rights conferred by the Crime Victims’ Rights Act by Judge O’Connor, also demanded the judge overturn provisions in the DPA that block Boeing from prosecution and consider taking other steps to hold Boeing accountable for its actions that led to the deaths of their loved ones.

“Despite increasing and perhaps legitimate criticism of these agreements, Congress—not the courts—is the appropriate venue to redress the inadequacies of this statutory enactment,” the judge wrote in his decision. “In our system of justice, a judge’s role is constitutionally confined to interpreting and applying the law, not revising it. For this court to step outside those constitutional bounds in an attempt to remedy wrongs it has no legitimate authority to correct would compound injustice, not see justice through.”

One of the criticisms of DPAs is that while they are filed in federal district courts, those courts have no authority to object to their contents. The topic has been addressed in prior federal appeals court decisions, including the 2015 case of Dutch aerospace company Fokker Servs B.V. and 2017 case of financial institution HSBC.

Boeing did not respond to a request for comment.