Two escort services have filed a federal lawsuit to halt a Utah solicitation law they fear could lead to the arrest of strippers or escorts who are simply acting sexy.

Utah defines solicitation as a person agreeing to sex in exchange for money. A new law that went into effect this month broadened the definition to include any person who indicates through lewd acts, such as exposing or touching themselves, that they intend to exchange sex for money.

It was intended to help law enforcement agents working undercover in prostitution stings, Salt Lake City Police Chief Chris Burbank said Friday.

He said it would protect officers who were being asked by prostitutes to expose or touch themselves to prove they're not police because making such requests as a precursor to offering sex for money is illegal under the new law.

"Officers were being put in a position that we're not going to allow, so we took a different direction," Burbank said.

Andrew McCullough, an attorney representing the escort services in the lawsuit filed May 9, said the law is so broad that it could allow police to arrest licensed employees of sexually oriented businesses, such as escort services or strip club dancers, for doing their job.

The expanded law includes language that makes a person exposing their genitals or touching themselves sexually an indication that they are offering sex. Those acts are legal in Utah for private strippers.

"Most girls who touch their breasts are not telling you they're open for sex," the attorney said.

McCullough said the law is "virtually identical" to one struck down by a federal judge as unconstitutional in 1988.

The Utah law could be used by police to hassle businesses protected by the First Amendment, McCullough said. For example, he said a semi-nude dancer at a strip club could be arrested for "suggestively thrusting."

Burbank said officers would not target anyone who is not a prostitute. Arrests will be made by undercover officers and only when it becomes obvious that a deal is being arranged, he said.

Utah House Minority Whip Jennifer Seelig, D-Salt Lake City, who sponsored the bill during the 2011 legislative session, said she worked with many different groups, including defense attorneys, to iron out legal issues with the law.

The intent is to target prostitutes, especially underage ones who are forced into the sex trade and trained to evade arrest, Seelig said. The arrest would be the first step in helping them get off the streets, she said.