Separated review – quietly furious take down of Trump’s inhumane border policy

The Trump administration’s southern border policy began with the dream of a wall in the desert and ended with the nightmare of family separation: children torn from their parents and loaded en masse into wire-mesh cages. It was inhumane treatment, which was precisely the point . The White House’s intention was to use terror as a deterrent and effectively write every parent’s worst fear into law. “When you have that policy, people don’t come,” Donald Trump said blithely. “I know it sounds harsh, but we have to save our country.”

Errol Morris’s forensic, procedural documentary walks us through the bureaucratic backrooms to show how the policy was hatched and implemented. It explains how its principal authors – Trump adviser Andrew Miller and attorney general Jeff Sessions – junked the pre-existing catch-and-release scheme (which had allowed migrants to remain in the country until their immigration hearing) in favour of a bold new tactic of forced separation and mass imprisonment. If Separated lacks the rueful exuberance that typifies much of Morris’s early work (The Thin Blue Line, The Fog of War, even last year’s John le Carré film ), that is entirely understandable. The material is sobering and the mountain of evidence needs unpicking. The film-maker handles his brief with the cold, hard precision of an expert state prosecutor.

Miller and Sessions unsurprisingly refused to be interviewed. But Morris does manage to secure an audience with Scott Lloyd, the grinning yes-man who was parachuted in to direct the Office of Refugee Resettlement. In following orders and pandering to his bosses, the amiable, star-struck Lloyd suddenly finds himself the de facto legal guardian of approximately 4,000 caged kids – or as one of his critics prefers to put it, “the most prolific child abuser in American history”.

One of the hallmarks of the Trump administration was its brazen skill at hijacking and defenestrating sedate federal offices, stuffing the desks with loyalists and forcing long-serving employees to either push back or bow out. Separated shrewdly allows these outraged, dogged public servants their moment on the witness stand – most notably Captain Jonathan White of the Unaccompanied Alien Children Programme, who is clearly still incensed by the level of mess he was first ordered to create and then to clear up.

Where the film falters, I think, is in the decision to intercut these potent talking-head testimonials with dramatised scenes of a Guatemalan mother and son’s fraught border crossing. While this complementary tale helps fill in the blanks of an operation that was largely conducted out of sight, in secret, it also draws attention to the total absence of migrant voices in the mix. Fair enough that Morris’s focus is the policymakers and foot soldiers. But a direct word from the victims might have helped his cause, too.

Leaked audio of traumatised infants, together with pictures of minors penned up like battery hens, eventually put paid to family separation. Confronted by mounting public anger and condemned by the pope, Trump hastily signed an executive order and declared the matter to be closed, and never mind that his subordinates were suggesting that the official list of separated children be strategically “lost” so as to protect themselves from legal action, and that as many as 1,000 remain unaccounted for even now. The cruelty was the point. In documenting Trump’s policy of family separation, Separated shows the route by which the US crossed over into darkness. It is an exacting, harrowing and quietly furious film.

• Separated screens at the Venice film festival.