Beginning March 13th, 2018, Michigan police officers are no longer legally permitted to have sexual intercourse with prostitutes in the course of their duties. Yes, you did read that law correctly. Until Governor Snyder signed legislation in December 2017, undercover police officers were allowed to entrap prostitutes during an investigation by giving money for sex while avoiding prosecution for themselves.
Why the change in the law? After Hawaii did away with a similar law in 2014, Michigan was the only state in the Union that allowed its police officers to have sex with prostitutes. Given the push to control human trafficking in the United States and eliminate victimization of sex workers, more people began to demand that governments eliminate the perceived double standard for cops. "These bills help ensure the ongoing integrity and accountability of our law enforcement system", Governor Snyder stated in a press release after signing House Bill 4355 and Senate Bill 275 into law on December 8th, 2017.
Despite whatever value that this legal shield may have had for law enforcement in combatting prostitution, this exemption generally attracted ridicule when mentioned on internet forums. It was often cited as a "loophole" that provided "extra benefits" to peace officers on duty.
An earlier version of the bill tried to remove the exemption for prosecution of police officers for any sexual contact whatsoever, but the final version signed by the governor only criminalizes sexual penetration. Nevertheless, the Michigan State Police has said that they do not train their officers to have intercourse with sex workers to further an investigation and they have never had any undercover cops exercise their immunity from prosecution under the old rule.