We're talking about two definitions of the word "Conviction": Kenny Waters, played by Sam Rockwell ("Moon"), is convicted of a horrific murder; his sister Betty Anne Waters, played by Hillary Swank ("Amelia"), is convinced he didn't do it. Therein lies this tale, based on their true story.

After a gruesome pan of a bloody crime scene, followed by the arrest of the accused, we flash back to a series of childhood vignettes in which we see Kenny, with Betty Anne loyally tagging along, get into one scrape after another. Their derelict mother is neglectful at best, so the two siblings can only depend on each other. We quickly learn that Kenny has an explosive temper and Betty Anne is always trying to save him from himself.

At the time of the murder, the best tool the forensic team has is blood type. The murderer has Type O blood, and so does Kenny; in addition, several witnesses testify that he confessed after they saw him in a bloody shirt; AND the prosecuting attorney is running for higher office. Based on these three elements, he is sent to prison for life with no parole.

After trying desperately to appeal the case, Betty Anne realizes her only hope is to get a law degree and do it herself. To the chagrin of her neglected husband (they soon divorce) and sons, she does just that. The only other "old woman" in law class is Abra Rice, played by Minnie Driver, who insists on becoming Betty Anne's friend. We get to watch these two chums wade into water waaaay over their heads as they try to re-open the case with help from a bungling bureaucracy and a non-profit group led by the durable Peter Gallagher ("Center Stage" and lots of TV).

We are treated to lovingly long closeups of both Hillary Swank and Sam Rockwell. His character ages believably, while hers never changes. Hmmm... It's nice to see Minnie Driver ("The Riches") again; plus Juliette Lewis ("The Switch") does a chillingly effective job as one of the witnesses. I can't tell you more at risk of revealing too much, but I was impressed.