HONOLULU, Hawaii (CNN/KGMB/KHNL) — The Honolulu Police Department, two of its officers, and the city itself are facing a lawsuit. It alleges that police forced a homeless man to perform a humiliating act in a restroom.

In December, officer John Rabago pleaded guilty to conspiring to violate Samuel Ingalls’ civil rights by forcing him to lick a urinal in a public restroom.

A lawsuit filed by Ingalls on Tuesday alleges that Rabago and another officer Reginald Ramones took him into a Sheridan Street restroom in January 2018 and that Rabago threatened to arrest him if he didn’t lick the urinal.

“These officers thought it was another form of amusement because, remember, one of these officers had a history of doing this,” said attorney Myles Breiner.

Ramones pleaded guilty to covering up the civil rights crime and has left the police force.

Rabago has been relieved of his police duties.

Breiner says Rabago told officers that he forced another homeless person to lick the urinal in a bathroom at Cartwright Field.

“Something like this shouldn’t happen but it frequently does,” said Breiner.

Rabago’s attorney Megan Kau says the incident was the exception.

“I think John made a mistake, he owned up to his mistake, he accepted responsibility and he entered a guilty plea,” said Kau. “This is not something happening on a day-to-day basis in the police force.”

Sources say a police internal investigation confirmed the civil rights violations, and that the HPD eventually referred the case to the U.S. Attorney’s office, leading to the guilty pleas.

Because the police officers were sued in their official capacity, the city and taxpayers could be on the hook if the lawsuit is successful.