'Déjà Vu' cranks up the message

From left: Stephen Stills, Neil Young, Graham Nash, and David Crosby in "CSNY Déjà Vu." (roadside attractions)

"CSNY Déjà Vu" may come as a big, spiky surprise to some fans of Crosby, Stills, Nash, and Young, much as the group's "Freedom of Speech" tour did in 2006. Instead of the warmed-over hippie nostalgia that comes from hearing four men well into their 60s warble "Helplessly Hoping" for the 4,673d time, the film, like the tour it documents, wallops you in the face with politics.

Well, good for CSNY - let it be duly noted that paying $300 a ticket does not necessarily mean a band has to meet your expectations or complacencies. (In other words, you pays your money and you takes your chances.) But because the film has a lot on its mind - the war in Iraq, the 1960s, modern-day activism, veterans' affairs, screaming guitar solos - "Déjà Vu" is as scattershot as it is ornery and cheering. Fittingly, the director is named Bernard Shakey, who any old patchouli head will tell you is really Neil Young.

Young was always the anarchist sparkplug of the group and probably its brains too - the rise in energy from 1969's "Crosby, Stills, & Nash" to 1970's "Déjà Vu" remains electrifying. In 2006, he had just recorded an album called "Living With War" whose first single was an in-your-face jeremiad titled "Let's Impeach the President," just in case you weren't sure where Neil stood on the matter. He then convinced the other three performers to turn the CSNY tour into a piece of rolling agitprop theater.

"It's a dictatorship, but it's a benevolent dictatorship," David Crosby says in the film. "Neil is in charge. He just thinks about this stuff all the time."

Young hired journalist Michael Cerre - a Vietnam vet who was embedded in the Iraq invasion for ABC News - to help structure the film and take cameras into the stands during the concerts. The results, especially in the red states, are choice.

When the band lays into "Let's Impeach the President" in Atlanta, grown men curse and storm the exits while college girls whimper that it's all "too political." The drama and high comedy of "Déjà Vu" lies in the collision of CSNY's boomer audience - who only want to be reminded of their youthful activism - with the band's unyielding insistence on the here and now. But why get involved when you can just sing along with "Ohio" again?

There's an entire movie to be made about such pop-cult hypocrisy (or, at the very least, about some concertgoers' unwillingness to do their homework beforehand), but Young wants more. The last half of "Déjà Vu" is largely devoted to those who've fought in Iraq and returned to fight against our presence there: congressional candidates, Gold Star mothers, a folk singer named Josh Hisle seen playing his song "A Traitor's Death" over there and back here.

These people and their efforts are as admirable as the film surrounding them is unfocused. Young wants to provide positive examples rather than lecture, but the devil in him can't resist poking those who think otherwise for the noisy feedback they provide while ignoring the group's own blind spots. (Where do the tour profits go? Veterans organizations? Crosby's health care?)

Young has always been a magpie, an intuitive collagist rather than a linear thinker, and it has served him well as a musician. Less so as a filmmaker. "CSNY Déjà Vu" is trenchant and inspiring in its broad outlines and sloppy in the details. (Minor point: the Boston Globe music critic, who's quoted in the film, is named Joan Anderman, not Anderson.) The movie makes you glad that CSNY is still out there rocking in the free world. It makes you doubly glad they're not leading it.

Ty Burr can be reached at tburr@globe.com. For more on movies, go to boston.com/movienation.