A sense of rising U.S. governmental secrecy and punishment of whistleblowers is the primary political takeaway from “United States vs. Reality Winner.” Sonia Kennebeck’s documentary chronicles the incarceration and trial of the titular young intelligence specialist who leaked an Nsa document revealing Russian attempts at interfering in the 2016 U.S. elections — intel the Trump administration was evidently keen on suppressing.

That her leakage of classified materials to media became the sole, punitive focus of prosecution, shutting out the issue of citizens’ need to know, provides the central moral conundrum here. But the film mostly backs away from a bigger picture of international espionage and possible Stateside collusion to focus on the personal level of Winner’s family, as her forced silence behind bars makes them her principal advocates. It’s an involving, empathetic if one-sided portrait whose limited insight into still-incendiary issues may actually smooth passage to broadcast,...