It remains unclear if the Biden administration would ask the court to grant an emergency stay to reimpose the mask mandate.
PHILADELPHIA (WPVI) -- The Justice Department is filing an appeal seeking to overturn a judge's order that voided the federal mask mandate on planes and trains and in travel hubs, officials said Wednesday.
The notice came minutes after the Centers for Disease Control and Prevention asked the Justice Department to appeal the decision handed down by a federal judge in Florida earlier this week.
A notice of appeal was filed in federal court in Tampa.
The CDC said in a statement Wednesday that it is its "continuing assessment that at this time an order requiring masking in the indoor transportation corridor remains necessary for the public health."
SEE ALSO: Justice Department to appeal order voiding travel mask mandate
It remained unclear whether the Biden administration would ask the appeals court to grant an emergency stay to immediately reimpose the mask mandate on public transit. An emergency stay of the lower court's ruling would be a whiplash moment for travelers and transit workers. Most airlines and airports, many public transit systems and even ride-sharing company Uber lifted their mask-wearing requirements in the hours following Monday's ruling.
A federal judge in Florida had struck down the national mask mandate for mass transit on Monday, leading airlines and airports to swiftly repeal their requirements that passengers wear face coverings. The Transportation Security Administration said Monday that it would no longer enforce the mask requirement.
The CDC had recently extended the mask mandate, which was set to expire Monday, until May 3 to allow more time to study the BA.2 omicron subvariant, which is now responsible for the vast majority of U.S. cases. But the court ruling Monday had put that decision on hold.
The CDC said it will continue to monitor public health conditions to determine if a mandate would remain necessary. It said it believes the mandate is "a lawful order, well within CDC's legal authority to protect public health."
According to Temple Law professor Craig Green, the appeal could take quite a bit of time.
"It could take a matter of weeks before the briefs are filed. It could take another number of weeks before oral argument in court," said Green.
Green thinks the Department of Justice may be using the appeal process to buy time for the COVID-19 numbers to go down.
SEE ALSO: Amid confusion, Philadelphia health officials hope indoor mask mandate won't last too long
"If the issue is no longer live and contested, the court of appeals will not hear the appeal. It's not going to affirm the district court's judgment. Instead, they say this whole dispute is moot. That's what the court of appeals would say, and the consequence of that is the district court's opinion would no longer have any legal authority at all," said Green.
But if Covid numbers were to go up, the federal government would be ready with their appeal.
"If the Covid numbers ramp up, then it's really important to have this appeal filed so the government can continue to defend its prerogative and power to impose a mask mandate," said Green.
White House press secretary Jen Psaki said Wednesday that Biden still is encouraging Americans to wear masks when traveling and that he had been "answering the question quite literally" a day before.
"People are not legally bound to wear masks," she said, after the court order. "So, it is a point in time where it is up to people - it is their choice, in that regard."
The appeal drew criticism from the U.S. Travel Association, which along with other industry groups had been pressuring the Biden administration for months to end the mask mandate for travel.
"Masks were critically important during the height of the pandemic," said Tori Emerson Barnes, the group's executive vice president of public affairs and policy, "but with low hospitalization rates and multiple effective health tools now widely available, from boosters to therapies to high-quality air ventilation aboard aircraft, required masking on public transportation is simply out of step with the current public health landscape."
The Associated Press contributed to this report.