Two Oscar-nominated documentaries begin exclusive engagements at the Royal this weekend, and the differences between them prove instructive. Alex Gibney’s Taxi to the Dark Side is an exceptionally well-structured exploration of the use of torture as a tool by US forces; what separates it from the great majority of War of Terror exposés is its underlying rigour. Gibney dissects the chain-of-command thinking that would permit (if not explicitly condone) the lethal use of force by American soldiers in their interrogations: the film takes off from the 2002 case of an Afghan cab driver named Dilawar whose brutal death was filed under “natural causes” until a proper investigation revealed it to be a murder.

That the victim was innocent of his alleged crime (he was brought in under suspicion of participating in a rocket attack; the real culprit was the man who turned him in) is not a small detail, but Taxi to the Dark Side resonates beyond a single tragic case. Gibney is attempting nothing less than an indictment of a military culture preaching attitudes of dehumanization, putting the lie to the oft-cited “bad apple” theory by exposing the rot at the root of the tree.

Taxi to the Dark Side doesn’t shy away from the visceral, but it largely stimulates feeling through thought; Sean Fine and Andrea Nix’s War/Dance eschews the latter almost entirely. These conspicuously well-intentioned filmmakers try out the old inspirational-story-against-a-hellish-backdrop trick, and while there’s no doubt that that the scenario — kids in a Ugandan refugee camp play underdogs in a nationwide music contest — has some pull, their technique is akin to series of cinematic cudgel blows: glossily rendered African vistas, nudging close-ups of stricken faces and flatly manipulative editing.