US police officer John Rabago admits forcing a homeless man to lick his urine so he won't be arrested in Honolulu, Hawaii.

Rabago, an officer of the Honolulu Police Department, Hawaii, admitted in federal court that forced 37-year-old Samuel Ingall to lick urine in a toilet bowl in a public toilet in January.

The incident happened after Rabago and fellow officer Reginald Ramones received a complaint that Ingall was causing a nuisance in the toilet of a shopping mall in Honolulu. Rabago said when the police arrived, Ingall refused to cooperate and initially gave a false name.

"If you lick your urine you won't get caught," Rabago then told the homeless man in a threatening voice. Fearing arrest, Ingall reluctantly obeyed Rabago's orders.

Rabago and Ramones were arrested and prosecuted earlier this year on charges of violating Ingall's civil rights. Ramones left the police force in August and pleaded guilty in September to a lower fine for knowing Rabago violated civil rights but did not notify.

Ramones acknowledged in court that Rabago had forced him not to disclose the story and persuaded him to delete messages related to the incident. Rabago still works at the Honolulu Police Department, but Hawaii New Now says he is likely to be fired as well as facing a 30-month prison sentence.

Judge Leslie Kobayashi concluded that Rabago had "intentionally forced Samuel Ingall to lick urine". Megan Kau, Rabago's lawyer, said in his trial on December 16 that the client was deeply sorry about what happened and that was why he decided to accept responsibility.