Given recent, unhappy developments in domestic discourse, there could hardly be a better time for a film about a homophobic jerk – partly fictionalised and entirely dead, so he can’t sue – who, after getting a hint of what it’s likes to be at the crappy end of the stick, gains some degree of empathy and understanding.

You might argue that the (deathly phrase) character arc in the fine Dallas Buyers Club is more than a little pat: beery Texan shagmeister Ron Woodroof (Matthew McConaughey), hitherto seen only in the company of like-minded folk, meets a transgender woman and realises LGBT people aren't quite so awful. But all studies show that nothing better dilutes bigotry than being among the company of those whom one once despised. There are truths worth heeding here.

The first US film from Canadian director Jean-Marc Vallée adapts a genuinely stirring true story from the darkest days of the battle against Aids. The film's version of Woodroof is a jobbing electrician and occasional rodeo rider who responds violently after being diagnosed as HIV-positive.

Unable to quite believe that he, a professional heterosexual, could have the “gay disease”, Woodroof initially decides to drink the problem away. Then the old Texan can-do mentality starts to kick in.

At this point, the Federal Drug Administration had yet to approve any effective retro-viral drugs, and the only hope was to be accepted on a trial for an experimental treatment such as AZT. Even then, the patient might find himself being given a placebo. Woodroof took to importing drugs from Mexico, Europe and Asia and – exploiting a loophole in the law – distributing them through a private buyers’ club. The patient was, technically, paying for his or her membership, not for the drugs themselves.

Let's get the McConaissance out of the way. The key to Matthew McConaughey's welcome ascension from rom-com drone to Oscar fave has been careful exploitation of his fairly limited range. It's unlikely we will ever see McConaughey succeeding as an Edwardian viscount or a Dutch nuclear scientist (though his hilarious cameo in The Wolf of Wall Street offers hope).

There is, however, nobody better at injecting nuance into the southern good old boy. Gaunt as his own ghost, the actor does a fine job of allowing inner intelligence – so far underexploited – to leak through Woodroof’s arrogant swagger.

Jared Leto also does fine work as the transgender woman who becomes Ron's colleague, educator and, ultimately, close friend. That performance is, however, based more on posture and appearance than on any great mining of personality. It's really just a first-class extended cameo.

Shot in a muddy haze by Yves Bélanger, Dallas Buyers Club kicks up some worthwhile questions about the American way of life. Though he eventually softens, Woodroof initially exceeds through sheer entrepreneurial drive. The buyers' club is a business, not a charity. Early on, without any apparent remorse, he turns away a patient for being unable to pay the required $400 per month. The doctors are allowed to make the case for caution in authorising medicine, even when dealing with terminally ill patients.

We could worry about the fact that, when addressing an Aids story, Hollywood still feels the need to put a heterosexual at the centre of the story. But, as McConaughey explained to this newspaper, this does allow the film to engage with bigotry and ignorance from a first-person perspective.

At any rate, for all its occasional compromises, Dallas Buyers Club shakes off potential disease-of-the-month TV movie status and succeeds at an uncomplicated emotional level. It is, in its way, a political picture. But it's also a properly moving one.