The ACLU has followed through on its threat to sue the Baltimore Police Department for deleting footage from a man’s cell phone after he recorded cops being overly aggressive with a woman they were trying to arrest.

The incident took place last year at the Preakness Stakes and police ended up deleting more than a year’s worth of footage from Christopher Sharp’s phone.

According to The Associated Press:

The suit filed by the American Civil Liberties Union of Maryland challenges the detention of Christopher Sharp, the seizure of his phone and the deletion of the recordings as unconstitutional. The ACLU argued that law enforcement officers in Maryland, including Baltimore police officers, “routinely threaten to arrest or punish civilians who document police activity, using the Maryland Wiretap Act and related, inapplicable infractions to back up these threats.”

The suit filed in Baltimore Circuit Court named the city’s police department, its commissioner and three unnamed officers. Baltimore police spokesman Anthony Guglielmi declined to comment on the pending case. But he said that if a cell phone is seized as evidence, the usual procedure would be to submit it to the evidence control unit and obtain a search warrant to review the video.

Sharp and two friends watched the Preakness Stakes last year from the grandstands and later went into the clubhouse, where Sharp noticed one of those friends being “forcibly arrested” and recorded the incident on his mobile phone, according to the lawsuit.

In a news release on the suit, the ACLU cites video shot by another bystander and posted on YouTube that shows officers struggling with the woman in a yellow skirt and sandals on the floor. Blood drips from her face as officers scream at her to put her hands behind her back.