On Wednesday night, a collaborator of the artist Robin Bell, who has been projecting words and images onto D.C. buildings for years, was arrested by Capitol Police. Capitol Police also seized a projector, laptop computer, battery, and stand as evidence, according to a public incident report provided by the Metropolitan Police Department.

Bell told WAMU Wednesday night was the third time they had projected messages onto the Rayburn House Office Building. This time, Bell said, they were projecting the words “Discrimination is Wrong.”

Bell has been working with projections in public spaces in D.C. for more than eight years. He opened a museum exhibit using his political projections at the Corcoran earlier this year.

“We were pretty sure we were pretty versed in the law,” Bell said. “The main thing is as long as it’s not an advertisement, we were pretty much told that it looked like we were able to do this, so it was a little bit surprising to see the commanding officer’s reaction.”

Bell also said an officer at the scene told him what they were doing was illegal because of a recent change in the law.

WAMU has not been able to obtain Capitol Police’s official report of the incident. A spokesperson for the department told WAMU the public report is still being processed. Capitol Police said in an email that officers did arrest an individual “for unlawfully demonstrating on Capitol Grounds by projecting an image on the Rayburn House Office Building,” and that the individual was charged with demonstrating in a prohibited demonstration area.

The Capitol Police also said D.C. laws regulate unlawful demonstration, though MPD’s Public Incident Report does not cite a D.C. code violation as the reason for the arrest.

Capitol Police said the laws governing unlawful demonstration have not recently changed, and did not confirm whether an officer at the scene cited a recent change in the law.

According to a Notice to Appear in Court provided to Robert Diesu, the man who was arrested, the arrest was for a violation of Capitol Traffic Regulation CTR 12.2.20. The officer who filled out the report added the note, “prohibiting the projection of images.”

But CTR 12.2.20 concerns prohibited demonstration areas, not projections. According to the Capitol Police website, the law prohibits demonstration activity on the steps of the U.S. Capitol, on the steps of any building on Capitol Grounds or in “any area otherwise closed or restricted for official use.”

Bell told WAMU they were on a sidewalk when the arrest happened. He said he had been told on other occasions by police that he needed to move locations, but on Wednesday night Capitol Police did not tell the group their location was the reason for the arrest.

Bell also tells WAMU that in his experience on Capitol Grounds, officers typically issue a warning before making an arrest. Bell said the group asked an assisting officer with Capitol Police whether he would consider issuing a warning instead of an arrest, but police did end up taking Diesu to Capitol Police headquarters. He was released and told to appear in court on April 17.

“Out of all the projections, we’ve done, this was the most middle of the ground,” Bell said. “But the reaction was pretty swift.”

Last year, Bell projected the message “Pay Trump bribes here” on to the Trump Hotel. He has also projected “Brett Kavanaugh is a sexual predator” onto the courthouse where Kavanaugh used to serve as a judge.

Bell said Wednesday’s projection was about LGBTQ+ equality.

“We’ve been pretty transparent about what we’ve been doing with eight years,” Bell said. “So we’re really trying to figure out where did this decision get made, and were they specifically targeting us.”

This story originally appeared on WAMU.