The Catholic students and chaperones who said they were kicked out of the Smithsonian National Air and Space Museum over their pro-life beanies have filed a federal lawsuit accusing the institute of violating their First Amendment rights.

The American Center for Law & Justice sued on behalf of nine students and three parents from the Our Lady of the Rosary School in Greenville, South Carolina, saying they were told during a Jan. 20 visit to remove their matching blue beanies with the message “Rosary PRO-LIFE” or leave.

“What the Smithsonian did is beyond reprehensible,” said ACLJ Executive Director Jordan Sekulow in a Tuesday statement. “These were students simply wearing a hat that passively expressed their support for life on the basis of their Christian faith. The way these students, many of whom were minors, were treated by their federal government — the Smithsonian and its employees — should shock everyone to the core.”

The lawsuit filed in U.S. District Court for the District of Columbia also accused the Smithsonian of violating the constitutional equal protection clause and the Religious Freedom Restoration Act.

Smithsonian spokeswoman Alison Wood apologized last week after museum staff confronted the students and chaperones, who toured the museum as part of a school trip to Washington, D.C., for the 50th annual March for Life.

“Asking visitors to remove hats and clothing is not in keeping with our policy or protocols,” Ms. Alison Wood said in a statement. “We provided immediate retraining that day to prevent a reoccurrence of this kind of error.”

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She acknowledged that “a security officer mistakenly told young visitors that their pro-life hats were not permitted in the museum.”

She added, “Smithsonian welcomes all visitors without regard to their beliefs. We do not deny access to our museums based on the messages on visitors’ clothing.”

The complaint said the staff also mocked and used profanity to refer to the pro-life group. The students were told to remove their beanies even though other visitors wore clothing with messages, including one who had on a PRIDE facemask.

One staffer allegedly said: “You need to take off your hats. We are a museum that promotes equality, and your hats do not promote equality.”