One of the best movies of the summer was one you didn't see.

"MC5: A True Testimonial" is a smart, swiftly moving account of one of the most influential bands of the 1960s, the Detroit-based MC5. David C. Thomas's thrilling documentary, which features rare footage of the band's early performances in Detroit clubs as well as insightful interviews with the MC5's three surviving members, has received rave reviews after a handful of screenings at festivals and a few theaters. The film was scheduled to play earlier this summer at AFI's Silver Theatre and Cultural Center in Silver Spring.

But in recent months. MC5 co-founder Wayne Kramer has prevented the filmmakers from acquiring rights to the use of the band's songs. In turn, Thomas and his producer, Laurel Legler, have filed a motion in federal court to ascertain how much of a say Kramer has in the disposition of the rights. Meanwhile, "True Testimonial" sits on a distributor's shelf.

The sad thing is that the journey of the film -- from years of work to festival circuit acclaim to legal fights to oblivion -- is something of a dog-bites-man story in the world of music documentaries. In any given year, critics, festival programmers and garden-variety fans see at least one or two terrific music documentaries at festivals or one-off screenings, hoping that audiences will be able to see them later in theaters. All too often, the filmmakers -- usually first-timers -- haven't secured rights to the music they've used in their films, either out of naivete or poverty. Or they sign a distribution deal, only to have their films' subjects (or, more likely, their agents/managers/lawyers) hold out for a bigger slice of the pie. Whatever the circumstances, "most of these stories end up with somebody paying through the nose," says Bill Banning, president of Roxie Releasing.

Banning should know. His company released the 1998 documentary "Kurt & Courtney," which singer Courtney Love tried to block. "I don't recall exactly what they said," Banning says of the letters from Love's lawyers, "but whenever we heard from them we would just turn the letter over to the press and turn it into publicity."

Lest readers get the wrong idea about Ms. Love, let it be known that she went out of her way to be generous with filmmaker Christopher Wilcha, in whose 2000 documentary "The Target Shoots First" Nirvana's music played a crucial role. Wilcha never secured rights to the music when he was showing the movie at festivals, but when Cinemax expressed an interest in airing it, he had to contact Love -- who controls her late husband Kurt Cobain's works -- to buy television rights. "I tried to go down every official, legitimate road to get to her and couldn't get past all the bureaucracy," Wilcha recalls. "But then I had this friend who'd been one of her nannies and she gave Courtney a tape. I got a phone call at 2 o'clock in the morning and it was Courtney saying she really liked the movie. She signed off on everything for $1,000." Wilcha is pursuing rights for a DVD but notes that Love "is not the most accessible person at the moment."

Still the, um, proactive nature of many artists' legal representatives has prevented scores of great films from being seen outside festivals and underground screenings. Indeed, rights issues have created some veritable holy grails among music film fans, including "Eat the Document," D.A. Pennebaker's second movie about Bob Dylan following on the documentary "Don't Look Back"; "Urgh! A Music War," a 1981 film featuring '80s icons such as the Police, Wall of Voodoo, the Dead Kennedys and XTC; "We Sold Our Souls for Rock and Roll," Penelope Spheeris's documentary about Ozzfest; and "Nobody Knows How to Talk to Children," a recent film about the White Stripes that has been so rarely seen that it approaches pop culture apocrypha.

Of course, in some cases, it's just as well that these movies are nipped in the commercial bud. "Just because it's unreleased doesn't mean it's a masterpiece," says Peter Lucas, a Seattle-based film programmer who has become an expert in unearthing obscure music films for venues including the Northwest Film Forum, Experience Music Project, Seattle International Film Festival and the Sound Unseen Film and Music Festival in Minneapolis. Lucas notes that in the ever-metastasizing world of media companies and outlets, "a lot of films are hung up on music rights because of transference of things between companies, so a small little distributor has some kind of limited rights to distribute a film for a certain amount of time. When it starts to get that complicated, I tell them, 'I'll talk to you later.' " Still, he adds, "You've got all these little microcinemas and bars and little places that are doing kind of under-the-counter screenings, so it's harder for the public to tell the legitimate distributors apart from the bars that are just popping in bootlegs."

Such under-the-radar shows have created their own legends over the years, movies that have been passed from friend to friend on bad dubs like so much VHS contraband. One brilliant example is "Superstar: The Karen Carpenter Story," Todd Haynes's 1987 experimental short that portrayed the tragic story of its title character using Barbie dolls (the effect was surprisingly moving). Haynes used the Carpenters' music throughout the movie, and Karen's brother, Richard, was not amused; he vowed to sue if Haynes ever released the movie in theaters.

That same year, Washington area filmmakers Jeff Krulik and John Heyn were showing friends a movie they had made several months earlier. "Heavy Metal Parking Lot" is a hilarious, somewhat alarming cinema verite portrait of young Judas Priest fans hanging out and getting wasted before one of the band's concerts. Although Krulik and Heyn never intended to show the film commercially -- "We just enjoyed making this stuff and enjoyed showing it to our friends," Krulik says -- the 15-minute short has acquired a major cult following that includes the members of Nirvana, Sofia Coppola, Spheeris and Baltimore icon John Waters, who told the filmmakers that the film gave him the creeps. ("We said, 'Wow, this is gold!' " Krulik recalls of that particular endorsement.) "Heavy Metal Parking Lot" became a favorite on the underground film circuit and even played such highfalutin venues as the Kennedy Center's film theater. Along the way, the filmmakers created a "Parking Lot" franchise, doing similar projects at a Neil Diamond show, a "Harry Potter"-crazed bookstore and a monster-truck rally. Recently, the cable network Trio showed "Heavy Metal Parking Lot," and for the first time since they made the film, the filmmakers were able to afford proper music rights (heretofore, Judas Priest had been kind enough to look the other way as the movie made its underground journey). Trio also commissioned six half-hour original "Parking Lot" shows, and Krulik and Heyn are hoping to sign a deal for a "Parking Lot" collection on DVD soon.

And there's more good news. "End of the Century," a documentary about the Ramones that became a hit when it was shown at festivals in Toronto and Berlin over the past year, is finally scheduled for theatrical release after a protracted struggle between the filmmakers and the band's managers (it's to open in Washington on Sept. 17). "Wattstax," Mel Stuart's 1973 documentary about a Los Angeles concert of Stax recording artists, is finally being seen with Isaac Hayes performing the theme from "Shaft," a sequence that was cut from the original film after MGM, which owned the rights to the song, threatened to sue. Even though their rights lapsed seven years later, the footage was lost until two years ago, when film editor Tom Christopher discovered the reels in a Los Angeles storage facility. The fully reconstituted version of "Wattstax" will be seen on PBS in early September, just as the DVD hits the street.

Then there's "Festival Express," a film nearly four decades in the making that will open here Sept. 3. The documentary of an epic 1970 train tour through Canada featuring the likes of Janis Joplin, the Grateful Dead, the Band and Buddy Guy is the result of years of persistent sleuthing and negotiating by director Bob Smeaton and producers Gavin Poolman, Peter Shukat and Ann Carli. "You figure out who the publisher is, then you call them up and say, 'We're doing this and how much will it cost?' " says Poolman. "Then you start the negotiating process." Although the sheer numbers of artists in the film -- many of whom are dead -- presented a daunting people-finding task, Poolman says, "most people were very businesslike when we eventually tracked them down. They all remembered the train journey incredibly fondly, which was helpful."

Smeaton, who has directed documentaries about the Beatles, the Who, Elton John and Pink Floyd, among others, had another secret weapon: "I know what musicians tend to be nervous about," he says. "I knew that in 'Festival Express' they wouldn't be nervous about what they looked like -- they were 30 years younger, after all. It would be about what the performances were like." Before going to the musicians, Smeaton and music producer Eddie Kramer carefully culled anything out of tune or less than show-stopping. In only one case -- when Poolman sent Ten Years After frontman Alvin Lee footage of their performance of "Love Like a Man" -- did a musician protest. "The audio wasn't very good," Smeaton says. "I knew that it was going to be a problem. I said, 'Don't send it to him.' We got a letter back saying it looks great, it's well shot, but the performance is substandard. And I said, 'I told you so.' "

But even when things go smoothly, no filmmaker is immune to the caprice of artistic temperament. Poolman notes that one band from the tour, Traffic, doesn't appear in the movie at all. "We have some fantastic Traffic recordings, but Stevie Winwood's management didn't seem too interested," he says. "We're hoping that once it opens they'll notice that it's a good film, and maybe we'll be able to clear the rights for the DVD."

The 1960s band MC5 in "MC5: A True Testimonial" and guitarist Wayne Kramer, below, who has shelved the film by withholding music rights."Festival Express," featuring Janis Joplin and others, opens here Sept. 3. "Heavy Metal Parking Lot," made in 1986, has been a cult favorite.Jerry Garcia, left, and Bob Weir in "Festival Express," about a 1970 train tour."End of the Century," starring the Ramones, will be released here Sept. 17.