Updated April 19, 2022 at 7:34 PM ET

The Justice Department said on Tuesday that it will appeal a federal judge's decision striking down the Centers for Disease Control and Protection's mask mandate for public transportation if the CDC determines the mandate is still needed to protect public health.

U.S. District Judge Kathryn Kimball Mizelle struck down the federal mask mandate for airplanes and other modes of public transportation Monday, writing in a 59-page ruling that the CDC had exceeded its authority and failed to follow proper rulemaking procedures.

Before the Justice Department's announcement Tuesday, White House press secretary Jen Psaki expressed frustration with the court's ruling.

"Public health decisions shouldn't be made by the courts. They should be made by public health experts," Psaki said.

Monday's court ruling quickly reshaped U.S. air travel, as a cascade of carriers from Delta and United to Southwest and American said masks are now optional for travelers aboard their aircraft.

Uber, Lyft and Amtrak have also chosen to end their mask requirements. Some major transit systems, including New York's Metropolitan Transportation Authority, will keep requirements in place for the time being.

The mask-wearing requirement had been imposed in early 2021, shortly after President Biden took office, in an effort to slow the spread of COVID-19.

Last week, the CDC extended the rules, which had been set to expire on April 18, through May 3, with the hope of allowing officials to take more time to study the BA.2 subvariant of COVID-19 which has been driving up case counts across the country.

"We do have upward trends of infections. CDC is responding to the data, and it's implementing the measure it has the authority to do," said James Hodge, a public health law professor at Arizona State University, in an interview with NPR.

In her ruling, Mizelle argued that the mandate violates the Administrative Procedure Act, as the agency failed to prove its decision regarding implementing the mandate.

The lawsuit was filed in July 2021 by two plaintiffs and the Health Freedom Defense Fund.

"The court concludes that the mask mandate exceeds the CDC's statutory authority and violates the procedures required for agency rulemaking under the APA," the judge wrote.

Last month, governors from 21 states sued the Biden administration to end the federal public transportation mask mandate, arguing that the continued enforcement "harms the states" and interferes with some local laws.

The filing came days after airline CEOs called on Biden to drop the mandate.

"President Biden's shortsighted, heavy-handed and unlawful travel policies are frustrating travelers and causing chaos on public transportation," Florida Attorney General Ashley Moody, who is leading the states' effort, said in a statement. "It's long past time to alleviate some of the pressure on travelers and those working in the travel industry by immediately ending Biden's unlawful public transportation mandates."

Eric McDaniel contributed reporting.

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