I have asked my friends, and most of them can reel off the names – the documentaries that changed the way they saw the world. Shoah’s account of the Holocaust, the 7-up series by Michael Apted – tracking the class differences that emerge with larval inevitability in the lives of British kids, Eyes on the Prize, Bowling for Columbine, Supersize Me. There is something specially powerful about documentary film, something both ineluctable and voyeuristic in the way that it takes you inside history.

This should be the Golden Age of documentary film, and in some senses it is. A profusion of television channels allows programs that cater to smaller and smaller markets. As viewers, we show an insatiable appetite for biographies of the famous – celebrity infomercials disguised as documentaries – but we also show a taste for quirkier material: Mad Hot Ballroom, Amy Sewell’s account of inner city kids doing ballroom dancing. Sing Faster, Jon Else’s documentary on Wagner’s Ring Cycle, seen from the stagehand’s perspective. There are documentaries about mental illness and spelling bees and Star Trek fandom – though not all in the same film. And the drop in the price of cameras and editing software, together with the availability of internet distribution, potentially puts a million documentarians on the streets.

But as Larry Lessig and others have pointed out, documentary film is rapidly becoming the latest victim of the explosion of intellectual property rights I have discussed in these pages. Ironically, the problem here is not a broadening of the rights themselves, but a “clearance culture” that demands licenses for the tiniest fragment of copyrighted material caught in the viewfinder or on the soundtrack of the documentary film. Imagine trying to sanitize your film of every song being played on a radio, every fleeting background shot of a copyrighted film or TV program. Imagine you are filming some kids, and one their cell phones rings, playing a copyrighted ring tone. That happened to Amy Sewell; the phone played the “Rocky” theme tune. The owners of the rights asked for $10,000 to clear it. Or imagine you need to refer to the cultural material of the time to tell your story; Eyes on the Prize, the great documentary on the American civil rights movement, was pulled from the shelves for several years because the painstakingly acquired licenses to the innumerable snippets of music, photos and news film needed to tell the story had all expired.

The law actually has pretty sensible rules to deal with such things. “Fair use” in the United States and “fair dealing” in the UK set up frameworks that allow the use of fragments of material to comment, report and criticize. The vast majority of the accidentally caught fragments of copyrighted material fit here, so do many of the deliberately chosen short segments necessary to make a point. If, on the other hand, I just take Elvis’s most famous songs and performances, and string them together in a “documentary,” fair use does not protect me. Nor should it.

But what the law says, and what film insurers require are often two different things. And film insurers hold the keys to the distribution networks. Their preference often seems to be that everything be licensed. As a result, some films do not get made at all. Others are shorn of copyrighted content, or their content deliberately falsified. What you see or hear is not really what happened.

Does this matter? I think so. Recently, our Center ran a short video contest. My own favourite was a film by Chris Sims called “An Army One By One.” Sims had been “embedded” with US Army recruiters in the North Carolina Piedmont region. But as he strove to capture the stories of the young men and women who are being invited to go and fight the war in Iraq, copyrighted music, TV and posters kept intruding. The jarring conflict between the cultural juvenilia around his subjects and the seriousness of the choice they were making was one of the central themes of his movie. “The US Army has been in Iraq for more than a year” Sims said, “and I am still trying to work out what I can keep in my film.”

Ironically, the biggest injury here may be to copyright itself. An entire generation of young film-makers now see it as nothing but an impediment, a source of hassles, ludicrous demands from clearances, and mind-numbing cease and desist letters. Yet that is not true. The reality they see has little to do with the law and everything to do with a culture of fear and misinformation.

This may be changing. Documentary filmmakers have issued a Best Practices statement on fair use. There is pressure on insurers to be more reasonable. But how to get the word out to the film students and the youthful digerati who will be the future of the medium? Two years ago at Full Frame, one of America’s leading documentary film festivals, a group of filmmakers challenged my colleagues and me to decode this reality in a way that human beings as well as lawyers could understand. When the Festival was held again this year, we returned with our answer – a comic book. (One reader noted that “law professors write comic book” sounds like the kind of joke that begins “The Pope, Jimi Hendrix and Kurt Godel walk into a bar…”) Writing it was a strange activity, and I fear the Dean has been given new reason to wonder about my mental health. But documentary film is a vital part of our culture and the people who will shape its future do not have lawyers, or read law review articles. It would be tragic if a pattern of ludicrous and legally ungrounded predatory behaviour stopped my kids from seeing their culture fully reflected in the documentaries to come, the ones that will change the way they see the world. Or perhaps even making those documentaries themselves.