Yes, common law does contain a "double jeopardy" principle: one cannot be tried for the same crime twice. A friend of mine who knows something about legal theory (I know next to nothing) points out that one can nevertheless face the same CHARGE twice. If I am convicted of stealing Fred's car it's just not true that the law can't touch me if I steal his car a second time - in the eyes of the law, which is not a complete ass, I have committed TWO crimes, even though they both bear the same description: `stealing Fred's car'.
Let us suppose, though, that it's different in the case of murder, at least in some jurisdiction somewhere. (It's easy to see why murder might be a special case.) Suppose that Libby Parsons, falsely convicted of killing Nick Parsons, now has the legal right to REALLY kill him. What of it? Murder is the ONLY crime Libby is at legal liberty to commit; but how does one commit ONLY murder? It's just not possible. In order to murder Mick, Libby must break any number of other laws: she must inflict grievous bodily harm, or damage property, or endanger someone's safety, or carry a concealed firearm, or create a public nuisance, or loiter, or jaywalk - I'm sure there are enough laws on the books to keep her locked away from precisely as long as if she'd simply been convicted of murder a second time, and a good thing too.
It's hard not to think of this when she JUMPS PAROLE in order to go in search of her presumed-dead husband. What's the point of this detail? The film wants to wave what it supposes to be a clever gimmick in our faces: the fact that Libby can commit murder within the law. If she then breaks a law - which she needn't have done, and which the film certainly needn't have been constructed so as to make it the case that she needed to have done - what's the POINT of the double jeopardy routine? I don't know that there was much point anyway. Do we really want this woman to break out of jail and murder her husband? Of course not. We like her. She's not yet a killer and we don't want her to become one, even if killing her husband is in her interest, which it isn't. This would have been a better film if Beresford had at some point halfway through made it clear to us that the "legal principle" Libby had heard from her friend in jail was but a distortion of the truth.
Anyway: this bugged me. But it's not to say that "Double Jeopardy" isn't otherwise a well-made thriller, distinctly enjoyable to watch. It has Tommy Lee Jones doing his schtick, for one thing. I actually prefer his character here to the one he bore in "The Fugitive". Everyone remembers his reply in the earlier film to "I didn't kill my wife": "I don't care." But it's a line that was just thrown in because it sounds cool. In "Double Jeopardy" Jones has a more discernible character, and he's more fun.
