Made at least 50 years ago, (may have been re-done I don't know)
Two guys talking about the death penalty (I think) one argues how easy it would be for an innocent man to be convicted of a capital crime, so he sets out to prove it, his safety net being that his friend knows the truth and will step in at the last minute to save him from execution.
Slight flaw in plan however, man is convicted and sentenced to die but his friend is killed and cannot come forward to save him.
Interesting movie -- one of the few in which George MacReady played the lead role. He had a facial scar from an auto accident that prevented him from playing romantic leads but which gave him an air of vague menace, perfect for playing suave villains. He's best remembered from his roles in Paths of Glory and Gilda, where he was one-third of a deadly love triangle with Rita Hayworth and Glenn Ford: