Biopics can be problematic affairs. They’re open to accusations of historic inaccuracy, being libelous, not being libelous enough, sanitising a life, tidying one up in the interests of simplification, and miscasting the crucial lead role. Fortunately, few of these problems befall Selma, a long overdue cinematic look at Martin Luther King’s struggle to guarantee the black vote in the face of ffeffgdvedgnjnctnvcubglwlcySouthern gerrymandering, following the passing of 1964’s Civil Rights Act.

Historians will work up a sweat working watching the electric exchanges between Tom Wilkinson’s vacillating LBJ and David Oyelowo’s stupendous King, taking issue in some quarters at the President’s wavering commitment to shoring up the landmark legislation (you know there’s a problem when Oprah can’t register to vote), while God alone knows what the late Hunter S. Thompson, would have made of Tim Roth’s George Wallace, but the background to the injustices is well delineated, and the sense of outrage palpable. Ava DuVernay’s film is frank and moving, without feeling egregiously manipulative.

Yet biopics only truly come to life when the subject under glass has the impress of the individual being recreated and it’s here, in Oyelowo’s performance, that Selma scores big. King’s power came from his faith and oratory and those rhetorical skills are much in evidence as the British actor, affecting a perfect Georgian drawl, tubthumps with an energy and earnestness that rouses us as much as those fortunate to be present at the original sermons.

DuVernay knows that King was no saint however, and she deserves credit for painting a human portrait of the late campaigner that doesn’t shy away from his adultery, his moments of self-doubt and actions that some supporters interpreted as moral cowardice. We also have a small but instructive intervention from Nigél Thatch’s Malcolm X, that serves to contrast King’s non-violent protest with X’s militant approach, the audience invited to ponder the relative gains and drawbacks of each in a system so badly stacked against those striving for greater equality.

Ultimately Selma works well as a companion piece to Steve McQueen’s 12 Years a Slave; the story of a different generation’s struggle that nevertheless illuminates the racial tensions that historically divided America, and continue to cleave the country socially, economically and culturally. The role of the biopic is to aid the understanding, both of the individual and the contexts that inform their live and story. On that metric, and many of the tradition ones, Selma can only be regarded as first rate.