"Adults can be adults," the Detroit Democrat says, "but when kids are exposed to this type of indecent material, I think it's important for us to stand up and draw the line."

Such signs on 8 Mile Road in Detroit prompted Hunter to introduce a bill, which the state Senate passed last month, that would restrict billboards for sexually oriented businesses to listing the business name and type, location and hours of operation. The bill is being reviewed by the House Transportation Committee, and Tupac says he hopes it will go to the House floor and become law by year's end. Callie Collins, Hunter's chief of staff, says some of the billboards on 8 Mile Road have already been taken down.

The bill is the latest salvo in a battle between states and the adult entertainment industry — a battle that the states, for the most part, have been losing.

In cases in South Carolina in August and in Kansas in July, laws meant to keep businesses from posting explicit billboards have been overturned by federal courts on First Amendment grounds. A similar law was overturned in Missouri in 2006.

In both cases decided this year, the states have decided against spending the money to fight a legal battle they feel is tilted against them.

"Given the state's budget challenges, it would be fiscally irresponsible to continue the litigation because there would be very little chance of success," said Ashley Anstaett, spokeswoman for Kansas Attorney General Steve Six.

"The state believes such an appeal's likelihood of success is slight," said Mark Plowden, spokesman for South Carolina Attorney General Henry McMaster. The issue, according to David Hudson, a scholar at the First Amendment Center in Nashville, is that in order to restrict free speech in advertising, the state must prove that the law's only purpose is to address "secondary effects" of such advertising, often cited as increased crime and decreased property values.

The argument that those businesses have such side effects has generally been speculative rather than proven, he said.

It's also hard to put anything on a billboard that would be legally obscene "if it has truthful information on it," he said.

J. Michael Murray, a Cleveland attorney who was part of the team that represented the sexually oriented businesses in the South Carolina and Kansas cases, said those rulings should make other states think twice before adopting billboard laws that would run afoul of the Constitution.

The argument that such signs are distracting to drivers and could compromise highway safety hasn't held up either, Murray said.

Hunter says his bill is different from the laws in those states, which were designed to keep such signs off the highways. His measure wouldn't prohibit billboards for sex-based businesses but focus on controlling the content of the signs, he said.

"They have a right to exist, but I feel there has to be a community decency standard applied," he said.

Daniel Weiss, senior analyst for media and sexuality for the Christian organization Focus on the Family, said he believes state and local governments could do more to regulate such businesses by stricter enforcement of obscenity laws as well as such things as building and health codes.

Barnett reports for The Greenville (S.C.) News