It's a classic movie scenario — two sexy stars rip each other's clothes off, get busy and then later light up a couple of cigarettes in bed.

Such a charged cinematic scene could earn a film an R-rating — because of the smoking.

Films in which actors light up may soon receive the same branding as nipple flashes and cursing: Lawmakers are looking to extinguish, or at least regulate, smoking on the big screen.

Anti-smoking activists want films with smoking in them to be given an R-rating. Most lawmakers have said they'd be satisfied if movie ratings included advisory information about smoking in films like they do for foul language, sexual content and violence. Meanwhile, movie lobbyist Jack Valenti (search) is defending Hollywood's right to have characters light up without interference.

The issue has heated up in the wake of the recent flap over indecency in the media, and because several studies have shown that teens are influenced to start smoking by watching screen idols do the same.

"What we're simply asking for is that smoking be treated by Hollywood as seriously as it treats offensive language," said Stanton Glantz (search), a professor of medicine at the University of California, San Francisco, who co-authored one of the studies.

According to Glantz's research, nearly 80 percent of movies rated PG-13 feature some form of tobacco use, while some 50 percent of G- and PG- rated films depict smoking.

But legislating big screen smoke scenes would be "very difficult to actualize," said Michael D. Friedman, an entertainment attorney in New York. "There will be a lot of push-back from the film and artistic community."

Valenti has staunchly fought smoking regulations, citing first amendment rights and artistic license.

"I don't believe that whatever the director does ought to incite the intervention of the government in any form," Valenti told the Senate Commerce Committee at a hearing last month.

Smoking is a major device that filmmakers use to help define characters, said Robert Thompson, professor of media and pop culture at Syracuse University, who pointed out that even Santa Claus lights up in films such as "Bad Santa."

"Good art is filled with people behaving badly," he said. "Smoking is still legal but unarguably so bad for you. That's one of the things that gives it such a charge — when you have a character smoking in a film it tells you a lot about them. They're flaunting the norms of what's considered safe and conservative behavior."

But Glantz wants to appeal to Hollywood's bottom line rather than argue over artistic choices.

If smoking were added to the list of criteria that would make a film R-rated, Glantz hopes filmmakers would be discouraged from depicting unnecessary smoking, such as the nicotine-addicted worm aliens in "Men in Black."  Because R-ratings limit the number of teens who can attend a film, these flicks earn less money and are therefore not as desirable in Hollywood.

"When you get into rating the film, which can have significant economic impact on the film, you'll find a lot of resistance," said Friedman. "Producers, actors and directors are going to want to depict characters the way they choose."

Another suggestion before the movie studios is to include a warning that there is smoking in a film, an idea that is "not all that controversial," said Friedman. 

However, Tinseltown is apt to try to avoid any regulation for fear that it will only open the floodgates to more demands.

"Where does this type of restriction and regulation end?" asked Friedman. "One interest group will say they don't want to see smoking on the screen, another will say they don't want to see something else ... I don't believe you can start selecting on a piecemeal basis."

Still, some officials have vowed not to let the smoking issue turn to ash.

"I guarantee you if something isn't done by the industry, there's certainly going to be efforts" by lawmakers, Sen. Ron Wyden, D-Ore., said at the hearing with Valenti.

Though the battle over smoking promises to be fierce, Thompson pointed out that the issue is ironic given the history of cinema.

"For many years Hollywood wasn't allowed to show sex through voluntary standards. The prevalence of smoking in classic movies was a replacement, like scenes with Humphrey Bogart (search) and his leading ladies where they light each other's cigarettes, it's very sexually charged," he said.

"Now it turns out the stand-in activity is as dangerous, or more dangerous, than the activity it was standing in for."

The Associated Press contributed to this report.