Yes, the title has two meanings, but that just makes it doubly obvious. There is not much poetry here, only belaboring: This conviction refers both to the guilty verdict that put a man in prison for many years, and to the certitude with which his sister then devoted her life to proving his innocence.
It actually happened, which means any movie about it might too easily seem like a TV movie. This one does. It has the advantage of Hilary Swank playing to her Academy-approved strengths, as a regular gal of modest means (unless you count her great fortitude), gradually rising to a challenge. And it has Sam Rockwell, an actor (and former San Franciscan) with an excellent sense of proportion and a gift for natural displays of conflicted conscience. But it also has an old familiar problem, which is that a well-organized fidelity to facts, no matter how remarkable those facts are, is not the same thing as a dramatic shape.
The facts are these. Betty Anne Waters (Swank), an uneducated bartender and mother of two from the small town of Ayer, Massachusetts, saw her only brother Kenny (Rockwell) put away for the brutal murder of a neighbor in 1983. She knew he didn't do it. So she got a GED, put herself through college and law school, became a lawyer, got in touch with more famous fellow lawyer Barry Scheck (Peter Gallagher) in the early days of his nonprofit Innocence Project, retrieved forgotten evidence from her brother's case and had it reevaluated in order to exonerate him. DNA testing didn't exist when her quest began, but became essential when it ended. That's how long it took.
And yes, that's enough for Bay Area screenwriter Pamela Gray and director Tony Goldwyn to craft a functional but unfortunately forgettable drama. Their movie, ever virtuous, also offers several strong supporting female performances: Ari Graynor as Kenny's waylaid daughter, Minnie Driver as Betty Anne's law-school friend, Juliette Lewis as Kenny's ex-lover and a dubious witness, and particularly Melissa Leo as the cranky cop who had it in for Kenny since day one.
Of course, being the only female cop on the Ayer police force in the early '80s might make anybody cranky; and Kenny, a hothead and a troublemaker at least since he and his sister were unwillingly separated as foster children, never seemed inclined to respect authority. But the movie doesn't make a priority of exploring that intriguing ambiguity, nor the related notion that this ostensibly inspiring story might also be read as a deeply disillusioning one.
Instead, it seems to worry that courtroom scenes and other legal procedures are inherently boring, whereas cloying childhood flashbacks are not. Lest it seem too arty for the less educated stock of working-class heartlanders whose lives it surveys, Conviction treats the Waters' sibling bond, and the ordeals it endured, with a too heavy hand. At worst, that seems patronizing; at best, it lacks a certain courage of conviction.