(SOUNDBITE OF UNIDENTIFIED FILM)

UNIDENTIFIED ACTOR #1: (As character) You got a match, Katie?

SCOTT SIMON, HOST:

There was a time when just about every adult seemed to smoke, especially in movies.

(SOUNDBITE OF UNIDENTIFIED FILM)

UNIDENTIFIED ACTOR #2: (As character) You're not trying to get rid of me, are you?

UNIDENTIFIED ACTOR #3: (As character) Don't be silly.

SIMON: The strike of a match, the flare of a flame, the swirl of smoke - all very elegant and photogenic on a movie screen, but smoking is bad for people, too. Should movies that show a character smoking miss out on a rating that would let it be seen by families and children?

A class action suit filed against the Motion Picture Association of America would prevent a movie from being rated G, PG or PG-13 if it has people smoking. The MPAA argues that their rating should be protected by the First Amendment. David Thomson is a film historian, critic and writer. He joins us from the studios of KQED in San Francisco. Thanks so much for being with us.

DAVID THOMSON: My pleasure.

SIMON: What's your immediate reaction to this lawsuit?

THOMSON: Well, I think it's a little silly. There are so many other things that are going on in films, like the willful crashing of cars, the abuse of people of other races, violence in general. And where does this process stop?

SIMON: So yours is, I guess, what constitutional lawyers would call the slippery slope argument.

THOMSON: Yeah, I think so. The other thing is that the rating system, in my opinion, has always been a fig leaf the film industry has employed to get past other possible legal dangers. I don't really think, in this day and age, that many kids are seeing movies because their parents say oh, yes, that's all right. I like the rating. You can go and see that film on your own.

This is not the way kids - people in general - are really experiencing films these days. They're seeing them at home, on TV, on the computer, on their phone, almost completely without parental control. Now, that's a sad thing, but it's a fact.

SIMON: I enjoy your writing. And I know you've inveighed against some of the inconsistencies of the rating system before. How do we explain a rating system where you might be reluctant to have children see somebody smoke, but it's all right if they see somebody disemboweled?

THOMSON: Well, I don't. I mean, I think that's horrific. And the movies have always been fascinated by showing us things that we do not normally see, forbidden things, taboo things. And they've always pushed that envelope. And I think there you're getting down to the basic commerce of the system. And the MPAA are quite candid in that they have been out there to protect the business. And the rating system was a way of protecting the business up against possible legal threat and intervention.

SIMON: Yeah. I don't know what the chances of success of this lawsuit might be, and certainly it would seem protracted at any case, but would there be some possibility that if the lawsuit or - would either prevail or to force the MPAA to make changes again - would this, in your judgment, get in the way of filmmakers doing an honest job of telling a story?

THOMSON: I don't think today it would really get in the way of it. But, you know, it does make you think of possible situations where, let's say, you might be watching Bette Davis and Paul Henreid in "Now, Voyager."

(SOUNDBITE OF FILM, "NOW, VOYAGER")

PAUL HENREID: (As Jerry Durrance) Shall we just have a cigarette on it?

THOMSON: The famous scene where he lights two cigarettes, he gives her one, has one himself, where a little legend comes across the bottom of the screen, don't do this at home, or something like that. It's a collision of time periods and the behaviors and attitudes that we associate with those time periods. And I think we risk looking a little foolish because of it.

SIMON: David Thompson, a film historian. He's author of "Moments That Made The Movies" and the upcoming book "Television: A Biography." Thanks so much for being with us.

THOMSON: Thank you. Transcript provided by NPR, Copyright NPR.