The illustrated sections are unnecessary, but Beat aficionado James Meredith is impressed nevertheless

The best art is immortal, but the biggest danger to art that defines its period is that when time moves on the work loses its impact.

Allen Ginsberg’s 'Howl' – first published in 1956 – is now regarded as one of the key works of 20th century poetry, and has been studied at schools and universities for decades. Back in Eisenhower’s America, – with its fear of nuclear Holocaust and ‘Reds under the bed’, and distrust of anything or anyone who refused to conform to the norm – it was attacked as perverse, obscene and downright un-American.

Directors’ Rob Epstein and Jeffrey Friedman (acclaimed documentary film-makers) attempt to give moviegoers a sense of what Ginsberg’s poem meant back then, and what it should mean today.

Howl isn’t a standard biopic of a historical figure (such as James Mangold’s vastly over-rated Walk the Line), nor is it as truly radical as I’m Not There, Todd Haynes’s 2007 exploration of Bob Dylan (which features a cameo from comedian David Cross as Ginsberg). Howl – shot in both colour and black and white – falls somewhere in between.

The poem itself is the main thread running through the movie, and scenes of Ginsberg (played with winning conviction by James Franco) passionately reciting 'Howl' publicly for the first time at the famous Six Gallery Reading in San Francisco are intercut with an interview Ginsberg gave in 1957.

This interview fills in the biographical details of Ginsberg's relationships with his fellow Beat writers Jack Kerouac, William Burroughs, Neal Cassady and Ginsberg’s lover, Peter Orlovsky. A recreation of the Obscenity trial of Lawrence Ferlinghetti, fellow ‘Beat’ poet, whose City Lights Books had published Howl and Other Poems completes the drama.

In what seems to be deliberately referential casting, the courtroom scenes feature Mad Men’s Jon Hamm (Don Draper) as defence attorney Jake Ehrlich (who’s real life escapades inspired the TV series Perry Mason), and Good Night, and Good Luck’s Jason Strathairn as prosecutor Ralph McIntosh. Veteran character actor Bob Balaban (who featured in US cinema’s first X Certificate movie Midnight Cowboy) plays presiding Judge Clayton W Horn.

A further thread running through the movie are animated sequences illustrating passages from the poem. This is the movie's major failing. Conceived by graphic artist Eric Drooker, and based on his 1992 collaboration with Ginsberg, Illuminated Poems, the animations are either obvious or literal: naked figures copulate, typewriters explode into flame.

The imagery within Ginsberg's poem is so powerful and original there is no need for second-rate company.

Thankfully, though, the film's strengths overcome this error of judgement from the film-makers. Franco, in particular, gives an impressive performance as Ginsberg. Although far too handsome (even with sticky-out ears and horn-rimmed glasses) to accurately portray the poet physically, he convincingly captures Ginsberg’s journey from awkward young Jewish scholar to playful, bold and inspiring beat rebel.

The camaraderie of the Beats is warmly evoked – though there is a little too much emphasis put on Kerouac and Cassady’s bisexuality, in my opinion – and the period details are accurate without being distracting.

Ultimately what Howl manages to achieve is to show the lasting power and greatness of the poem, as well as reflecting the on-going battle between censorship and freedom of expression. Ginsberg would be a happy man.

Howl is showing at QFT Belfast until Thursday March 10.