Lenny Bruce used to ask why it was obscene to show sex in American movies but not violence. Fifty years later, our screens remain washed in red, with severed if not necessarily naked body parts. More than half of the mostly American titles that received R ratings last year contained some kind of violence (as in strong, bloody and “grisly bloody violence and torture”) while only a third had sexual content. No NC-17 ratings were handed out, which bar youngsters, the viewers the studios most lust after.

One film did receive an NC-17 last year, if only fleetingly: “Blue Valentine,” a bruising independent drama about a marriage that goes south starring Ryan Gosling and Michelle Williams. The scarlet letters were for what was vaguely described as “explicit sexual content,” words interpreted to mean that the ratings board had freaked out at the realism or perhaps intimacy of the sex, including an instance of oral sex and another scene in which the unhappy couple make uncomfortable, crushingly sad love. The movie’s combative distributor, Harvey Weinstein, successfully appealed the NC-17, and the rating was changed, without cuts, to an R (for its “strong graphic sexual content, language and a beating.”)

When I saw the original version of “Blue Valentine” at the Sundance Film Festival last year (the film was subsequently trimmed before it was rated), I wasn’t shocked by the sex — after all, it’s about two lovely young people who can’t keep their hands off each other — but I was startled. American characters — heterosexuals! — were having sex in a movie. Even at this pre-eminent independent festival, American filmmakers shy away from sex, especially the hot, sweaty kind. The old production code might have crumbled in the 1960s and couples can now share a bed, but the demure fade to black and the prudish pan — coitus interruptus via a crackling fire and underwear strewn across the floor — endures.

Image Credit... Jessica Walsh

The recent deaths of the actresses Lena Nyman and Maria Schneider were poignant, useful reminders that there was a time when Americans used to troop in droves to go watch serious or serious-enough movies, domestic and imported, in which sex mattered as much if not more than violence. Ms. Nyman, a theater student turned screen siren, starred in the notorious 1969 Swedish film “I Am Curious (Yellow)” and its less popular sequel released three years later, “I Am Curious (Blue).” Ms. Schneider remains best known for holding her own, sometimes naked, against a more coy Marlon Brando in “Last Tango in Paris,” the Bernardo Bertolucci landmark (and French-Italian coproduction) that forced audiences to regard butter in a new light much as Hitchcock’s “Psycho” had forced them to reconsider the shower.