The mandate, enacted in February 2021, is unconstitutional because Congress never granted the Centers for Disease Control and Prevention the power to create such a requirement, U.S. District Judge Kathryn Kimball Mizelle said in her order issued April 18.
“Congress addressed whether the CDC may enact preventative measures that condition the interstate travel of an entire population to CDC dictates. It may not,” the order says.
While the government argued that the definition of “sanitation” in federal law allows it to create travel restrictions like the use of masks, Judge Mizelle disagreed.
“A power to improve ‘sanitation’ would easily extend to requiring vaccinations against COVID-19, the seasonal flu, or other diseases. Or to mandatory social distancing, coughing-into-elbows, and daily multivitamins,” she wrote.
The Biden administration has extended the mask mandate several times since it was first announced. Most recently, the mandate was extended last week and was set to end May 3.
The rule has been alternately praised and criticized by airlines, pilots, and flight attendants. Lawsuits have been filed over the mandate, but Judge Mizelle ruled in favor of two people and the Health Freedom Defense Fund, who filed suit in July 2021.
It is not yet clear if the Biden administration will appeal the decision.
A version of this article first appeared on WebMD.com.