It’s already been called the most important civil rights film of the decade, but only time will tell if Milk has any real impact on the gay marriage issue or any other related civil rights matter. Obviously the film, which is set thirty years in the past, can be appropriated by the campaign to overturn Proposition 8, but if that campaign is successful, it will be difficult to prove with certainty Milk contributed to the end result.

The Birth of a Nation may have inspired a reformation of the Ku Klux Klan and Guess Who’s Coming to Dinner may have opened some minds to wider acceptance of interracial marriage (which had just recently been legalized). However, as Time magazine reported earlier this year, it’s quite rare for cinema to really change the world. A movie like Philadelphia easily gets moviegoers thinking about AIDS and discrimination, for instance, and Sicko exposes some of the supposed benefits of universal health care, yet most of these kinds of message films preach primarily to the choir.

But at least five films have made an actual difference, either on a local or national level. Will Milk join the small group of movies detailed below?

Victim (1961)

Long before Milk, Philadelphia or even Cruising, this British thriller became the first motion picture in history to feature the word “homosexual.” At the time, same-sex acts were illegal in the UK, and so, even though the laws weren’t strictly enforced, the film was quite controversial (and it was banned in the U.S.). Still, this story of a closeted bisexual lawyer who becomes the target of an anti-gay extortion ring had a deep, lasting effect on the people in Britain, and it’s unofficially yet widely considered to have influenced both general acceptance of homosexuality and the 1967 Sexual Offenses Act, which legalized consensual same-sex relations across the pond (anti-sodomy laws in the States, on the other hand, were not completely eliminated until 2003).

I Am Curious (Yellow) (1967)

It may seem extremely tame by today’s standards (in the recent words of John Waters, it’s nothing more than a “limp dick and some ugly women naked.”), but this warmer-titled of Vilgot Sjoman’s I Am Curious films became infamous for its depiction of full frontal nudity and an oral sex act that could barely be called fellatio. After being banned in Massachusetts, where it was labeled pornography, it became the subject of an obscenity case that went all the way to the U.S. Supreme Court, where it was ultimately determined not to be obscene. Once it could be freely distributed, it became a must-see, though many were disappointed with it, and it held the record for highest grossing foreign film in the U.S. for more than twenty years. More importantly, the Supreme Court decision was groundbreaking in terms of obscenity law, and the multi-billion dollar pornographic film industry of the 70s was able to happen as a result of this one little Swedish art film.

The Thin Blue Line (1988)

This Errol Morris film is considered one of the most influential documentaries of all time, for a couple of reasons. In addition to being significant to the craft of nonfiction cinema, it also had a direct effect on the freedom of one man. Rather than merely present the story of Randall Dale Adams, who was tried and convicted of murdering a Dallas police officer, Morris also investigates the case, with enough detail to convince viewers of Adams’ innocence. Following the release of the film, Adams was able to get his conviction overturned and eventually was released from prison. While rescuing one individual may not be the same as changing the world, The Thin Blue Line is considered one of the only motion pictures to be directly influential in bringing about some kind of change.

JFK (1991)

Oliver Stone’s controversial look at the Kennedy assassination didn’t exactly tell us who killed the president. It didn’t even convince everyone that Oswald wasn’t responsible. But despite all the controversy and negative reviews, JFK went on to be a landmark film for its cause, because it led to the passage of The President John F. Kennedy Assassination Records Act of 1992 (aka the JFK Act) and the formation of the U.S. Assassination Records Review Board. Officially, Congress was more annoyed by the conclusions of JFK than inspired by the film, but the result just goes to show (and Michael Moore likely was paying attention) that being a burden can be as worthwhile as being convincing.

An Inconvenient Truth (2006)

Davis Guggenheim’s film of Al Gore’s Global Warming presentation didn’t bring about a lot of change or legislation in the U.S., but it did have a significant effect in terms of breaking ground on discussion of the issue. However, it was apparently instrumental in the passing of a law to curb greenhouse gases in California. Meanwhile, elsewhere, it has been employed in school curriculum and it certainly helped Gore win the Nobel Peace Prize. Because not all films can be as direct and quickly effect as The Thin Blue Line and JFK, though, we’ll need more than the past two years to fully see the difference made by this one.