Even if you don’t know what the Motion Picture Association of America is, you know its work. The G/PG/PG-13/R/NC-17 system is their baby, designed to help parents decide what is safe viewing for their children. Of more than 30 similar agencies surveyed worldwide, the MPAA is the only one to operate in complete secrecy; no one knows who makes up the ranks of the raters, nor what their criteria are. Creator and former chair Jack Valenti often said this was to protect the board from “outside influences,” which would be a noble sentiment if the MPAA didn’t answer to—and only to—the seven largest studios in the country.

You see, the MPAA is “voluntary.” It’s set up by the studios and not by the government so the movie industry can appear to be self-regulating. Conveniently, this means civil necessities like “transparency” and “public accountability” are sidestepped. Likewise, a filmmaker does not have to submit his or her film to the MPAA to get it shown. But since the MPAA is hooked up to every major studio, distributor, and theater chain in the country, not getting an MPAA rating is tantamount to committing career suicide. Sure, you can get your film made. But if no one in the country will promote it, carry it, or exhibit it, what exactly was the point?

This kind of de facto censorship has angered filmmakers and critics almost since the rating system’s inception. Because the studios have decided that 15 year-old boys with an allowance and a ride to the cineplex are the demographic sweetspot, films of all stripes have been pared down to meet those boys’ needs, even if those boys were never the intended audience. Those same 15 year-old boys are the reason we see a yearly glut of poorly-made, poorly-conceived PG-13 horror films that lack any visceral punch. These are the same cheap, gormless horror films that later release “unrated” DVDs to double-dip on the 15 year-old boy’s disposable income.

Or consider the case of Stanley Kubrick. His last film, Eyes Wide Shut, was originally rated NC-17, for graphic sexual content. The context of the graphic sexual content makes the material less than titillating, but nevermind; appreciation of context has never been the MPAA’s strong suit. Because the studio demanded an R rating before distributing the film, Kubrick was forced to cut material and insert CGI figures to “block out” some of the worst offenders. (The MPAA hates, hates, hates pelvic thrusting.)

The exercise was nothing short of ridiculous; the film was never intended for younger audiences, so the editing changed absolutely nothing about the makeup of who actually went out and bought tickets for it. Instead, those same audiences got a compromised piece of art. Everyone lost: Audiences were robbed of the full experience, and the artist was not allowed to show his complete vision. All, of course, to protect the children. Children who never saw the movie.

And then there’s the MPAA’s treatment of independent films. Matt Stone, one half of the South Park brain trust, tells of when he and Trey Parker were making their porn star superhero epic Orgazmo. The MPAA gave that film, independently released and distributed, an NC-17, and wouldn’t tell Stone or Parker why or what to cut to get an R. They were simply told to keep cutting and resubmitting until they hit the mark. South Park: Bigger, Longer, and Uncut, distributed by Paramount, was returned from its first MPAA screening with an exact list of what had to be cut to get an R rating. Anyone who’s seen both films knows the R-rated South Park makes the NC-17 Orgazmo look downright prudish.

But then indie films get a hard time across the board. Particularly illuminating is a parade of “offending” sequences from NC-17-rated indie films, shown side-by-side with almost identical sequences from R-rated studio films. Hmm. Now why would a studio-sponsored ratings board be more forgiving of wide-release studio pictures? If the phrase “conflict of interest” comes to mind, friend, you aren’t alone.

These and other issues are the central points of This Film Is Not Yet Rated, a lightweight yet acidic documentary with anger to spare. Other questions raised: Why is the MPAA so viciously pursuing film piracy, when those pirates are often those same 15 year-old boys? (Because piracy is a conveniently untrackable scapegoat, that’s why.) Why is the MPAA so prude about sex and yet so lenient about violence and gunplay? Why is the MPAA so squeamish about the depiction of the facial expressions of women in orgasm? And why, if a filmmaker decides to make an appeal on an unfavorable rating, must he face a panel of anonymous members (actually high-level corporate officers in major studios, distributors, and theater chains, and two representatives of the Catholic and Protestant clergy) who won’t allow the him to cite precedent in other MPAA-rated films?

Filmmaker Kirby Dick follows two paths throughout: Interviews with filmmakers, critics, first amendment lawyers, and authors, all of whom have done battle with the MPAA in the past. Surprisingly, director John Waters comes off as the most articulate and intelligent of a smart bunch, and his insights and experiences are the most revealing.

The other path follows a private investigator hired by Dick to uncover who, exactly, works on the ratings board. This tangent is less successful; I suppose every doc maker feels it incumbent on himself to break the monotony of talking heads with Michael Moore-style hilarity, but here it’s just a distraction. Just when Waters or Stone or David Ansen of Newsweek gets to something particularly deep or interesting, Dick whisks us back to the IFC’s version of Dog the Bounty Hunter.

But what the PI finds is interesting nonetheless. All raters, for instance, are supposed to have children between the ages of 5 to 17, to fit the “normal parent” requirement. Most have children 25 or older. And what, asks director Jamie Babbit (But I’m a Cheerleader), constitutes a “normal parent”? The ratings board appears to be made up mostly of upper-middle class WASPs, so their answer would be obvious: other upper-middle class WASPs. The subtext is present throughout: a small group of people who answer to no one but the industry’s biggest moneymakers have been steering and censoring the world’s most popular art form for nearly 40 years, using a system of morality no one has ever been allowed to see, let alone scrutinize.

Every film lover should see this documentary. Digressions to silliness aside, it is an entertaining and occasionally enlightening experience. The energy is infectious; This Film is anarchic, relevant, interested and interesting. It may even anger you. But it is necessary to your education of how the movie system works; consider This Film Is Not Yet Rated a primer on one of the more interesting and controversial stories behind the stories.

That is, of course, if you can find a theater that’s showing it. This Film Is Not Yet Rated is rated NC-17.

I wonder why?