The US Justice Department announced on Tuesday that it will appeal a court decision that overturned the federal government’s mask mandate for travellers – but only if the US Centers for Disease Control and Prevention deems that the rule is still necessary to protect public health.

“The Department of Justice and the Centers for Disease Control and Prevention disagree with the district court’s decision and will appeal, subject to CDC’s conclusion that the order remains necessary for public health,” spokesperson Anthony Coley said in a statement.

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“The Department continues to believe that the order requiring masking in the transportation corridor is a valid exercise of the authority Congress has given CDC to protect the public health. That is an important authority the Department will continue to work to preserve,” Coley said.

Before the mandate was overturned, the Biden administration extended the rule through May 3, requiring masks to be worn on public transportation, flights, trains, and within airports. The CDC was scheduled to evaluate whether the mandate was still necessary until May 3, and Coley stated that any appeal would be filed after that date.

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“If CDC concludes that a mandatory order remains necessary for the public’s health after that assessment, the Department of Justice will appeal the district court’s decision,” Coley said.

The move comes after the Justice Department spent much of the previous day debating whether to appeal a court judgement that surprised much of the government, airline industry, local public transportation departments, and ordinary Americans. An appeal would mean that the administration would seek an extension of the mandate from a higher court, despite the fact that many airlines and public transportation networks have already decided to make masks optional as a result of the court order.

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If an appeal is filed, it will be a dangerous move that will limit the government’s capacity to issue similar mandates in the future. If the 11th Circuit, which hears appeals from Florida, maintains the order overturning the mandate, it will set a precedent for all other federal courts in that circuit, which covers the Southeast. A Supreme Court decision affirming the lower court’s decision to overturn the mandate would make the judge’s findings about CDC authority binding nationally.