This is the second politically-charged documentary of the election season from activist director Robert Greenwald, and it’s less structurally ambitious but definitely more important than “Outfoxed,” his assault on Fox News. “Uncovered” is basically a talking-head piece that argues that the Bush Administration’s decision to invade Iraq was ideologically motivated and involved a deliberate misuse of evidence in an effort to persuade the American public and world community that the policy was justified. There’s no attempt to invest the presentation with a false sense of balance; equal time is hardly afforded to proponents of the official line, who are shown in an unflattering light if at all. Nor does Greenwald work with the same talent for mockery and black humor that Michael Moore has cultivated.

But objectivity and satirical bite are hardly the points of a straightforward exercise in political polemic like this. The intent is to present what’s effectively a legal brief against Bush policy, and the argument “Undercover” presents is a formidable one. Excerpts from some thirty people are included, and they’re a knowledgeable, articulate lot. They range from well-known figures like Joseph Wilson, Richard Holbrooke, Richard Clarke, John Dean, Scott Ritter and Henry Waxman to bureaucrats and journalists who aren’t so familiar, and Greenwald has arranged their testimony effectively to construct a relentless critique of the president’s war planning and political agenda. Those who disagree with the conclusions will complain that the data are one-sided, but that’s the nature of the beast. Given its premises and purpose, “Uncovered” hits the bulls-eye. And those who passionately reject its findings are certainly welcome to take up their pens and cameras in response. Indeed, many of them already have.

Films like “Uncovered” are basically preaching to the choir, of course. But that doesn’t mean that the sermon isn’t one that needs to be heard.