“Ernie & Joe: Crisis Cops,” Jenifer McShane’s nonfiction portrait of two officers working in the San Antonio police department’s mental health unit, arrives at a time of continued debate about what constitutes excessive policing. For Ernie Stevens and Joe Smarro, the goal is to defuse potentially violent encounters with the mentally ill and steer them into treatment instead of jail.

While it seems as if policing with empathy would be a basic law enforcement principle, archival footage that McShane (“Mothers of Bedford”) places early in the film shows imagery that has become all too familiar: a police officer pulling the trigger when faced with an emotionally disturbed person. That horrific fatal police shooting in Dallas, involving an officer’s confrontation with a schizophrenic man holding a screwdriver, iterates what many viewers already know: The system is broken.