SAN FRANCISCO (KCBS) — A law that allows Hawaii police officers to have sex with prostitutes while working undercover investigations leads to further abuses of women by police, according to a San Francisco research group working to abolish prostitution and human trafficking.

The law gained national attention after a bill to toughen state laws on prostitution did not include an exemption for police officers. Honolulu police have urged state lawmakers to keep the exemption, saying that revealing identities too soon could ruin investigations and that procedures exist to prevent officer misconduct.

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But critics, like Melissa Farley, executive director of Prostitution Research and Education, told KCBS that giving undercover cops a free pass isn’t necessary and can further victimize sex workers.

“I’m not aware of it anyplace in the United States, or the world, where cops are permitted to sexually exploit those in prostitution—legally,” she said.

“We all know it goes on but usually a police force will challenge, arrest or fire a cop that extorts sex acts from somebody in prostitution; It’s an abuse.”

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Prostitution isn’t legal in Hawaii but it is prevalent and proposed law would focus on people who are underage. About 90 percent of prostitution is pimped, Farley said and the law would hopefully afford greater penalties for people that use women in prostitution.

The Hawaii bill cracking down on prostitution was originally did not include the exemption for officers on duty, but it was amended to restore that protection after police testimony. The revised proposal has passed the state House and was set to go before a Senate committee Friday.

Police haven’t said how often – or even if – they use the provision.

“There are a lot of good cops out there. The last thing we need to be doing in Hawaii, or anyplace else, is codifying into law an abusive practice that most of the rest of the states are trying to get rid of,” Farley said.

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Listen below for the entire interview between KCBS’ Rebecca Corral and Melissa Farley, executive director of the San Francisco-based group Prostitution Research and Education.