The justice department said it would appeal Monday’s ruling by US district hudge Kathryn Kimball Mizelle if the Centers for Disease Control and Prevention determined the mandate was needed to protect public health.

“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,” the justice department said in a statement.

Before Monday’s ruling that overturned the mandate requiring mask coverings on planes, trains and other public transportation, the mandate was due to expire on 3 May.

“We will continue to assess the need for a mask requirement in those settings, based on several factors, including the US Covid-19 community levels, risk of circulating and novel variants, and trends in cases and disease severity,” a CDC spokesperson said in a statement on Tuesday.

The CDC reiterated its recommendation that people wear masks on public transportation while indoors. The court’s order had caught the administration by surprise and left it struggling to grasp its impact both on the requirement’s end and on CDC’s authorities going forward.