WASHINGTON (Reuters) -Families of some victims of two Boeing 737 MAX plane crashes that killed 346 people asked a U.S. appeals court on Thursday to reverse a judge's decision to approve the Justice Department's request to dismiss a criminal case against the planemaker.

Judge Reed O'Connor, of U.S. District Court in Fort Worth, Texas, last week approved the request by the Trump administration's Justice Department, but harshly criticized the government's decision.

He said he did not agree that dismissing the case, which had been pursued under the Biden administration and initially resulted in an admission of guilt, was in the public interest.

The families asked the 5th Circuit Court to reverse his decision. They said the Justice Department violated their rights as crime victims when it negotiated a deferred prosecution deal with Boeing over a fraud charge stemming from false representations the planemaker made to the Federal Aviation Administration.

"We believe that the courts don't have to stand silently by while an injustice is perpetrated," said Paul Cassell, a lawyer for some of the families. "The charges against Boeing cannot simply be dropped."

Boeing did not immediately respond to a request for comment on Thursday. The Justice Department last week rejected the judge's criticism and said it believed the deal was "the most just outcome."

   O'Connor said in 2023 that "Boeing's crime may properly be considered the deadliest corporate crime in U.S. history."

He said he had no authority to reject the government's decision to make a deal with Boeing, even though it "fails to secure the necessary accountability to ensure the safety of the flying public."    Boeing last year had agreed to plead guilty to a criminal fraud conspiracy charge after the fatal 737 MAX crashes in Indonesia and Ethiopia in 2018 and 2019.    After U.S. President Donald Trump took office, the Justice Department reversed course in May and dropped the demand for a guilty plea.     Under the deal, Boeing agreed to pay an additional $444.5 million into a crash victims' fund to be divided evenly per victim of the two fatal 737 MAX crashes, on top of a new $243.6 million fine and more than $455 million to strengthen the company's compliance, safety, and quality programs.    In September, the FAA proposed fining Boeing $3.1 million for a series of safety violations, including actions tied to a January 2024 Alaska Airlines 737 MAX 9 mid-air emergency, and for interfering with safety officials' independence.

Separately, a jury in Chicago on Wednesday ordered Boeing to pay more than $28 million to the family of Shikha Garg, a United Nations environmental worker who was killed in the crash in Ethiopia. Under a deal between the parties, the family will receive $35.85 million - the full verdict amount plus 26% interest - and Boeing will not appeal.