Editor's note: Alan Dershowitz is the Felix Frankfurter professor of law at Harvard Law School.
Cambridge, Massachusetts (CNN) -- The jury in the John Edwards case rendered exactly the right verdict. Of course they couldn't make up their mind on most of the charges. No rational person could. The judge essentially instructed them to get into John Edwards' mind (as well as into the minds of several other actors in this political soap opera) and to determine precisely what his intention was in receiving money from friends.
If his intention was primarily personal (to try to save his marriage and not humiliate his wife any further), then there was no crime. But if his intent was primarily political (to help him get elected president), then there may have been a crime. Precisely how many angels were dancing on the head of that pin?
No one, not even Edwards himself, could calculate the precise quantification of his complex and multiple intentions. This kind of decision should never be the subject of a criminal case, and the jury was right to find a reasonable doubt as to one of the charges and to throw its hands up as to the others.
All reasonable people should now hope that the Justice Department sees the light of day and does not seek a retrial. The jury has spoken, though ambiguously, and there is no reason to believe that another fairly picked jury will be able to discern the precise intentions of the actors with any greater certainty or precision.
This entire farce of a trial is part of a larger problem that infects not only America but other Western countries as well: the criminalization of policy differences and of personal sin.
No one can justify what John Edwards did to his family, to American politics and to himself. He will forever pay a steep price for his selfishness and arrogance. But it is not a price that all Americans should have to pay by the distortion of the criminal justice system into a Rorschach test, in which the jury is asked to interpret vague action and attribute precise intentions to actions done with mixed motives.
The criminal law should be limited to what I call "Hamlet decisions." Before a person is charged with a serious crime, the government should have to prove beyond a reasonable doubt that the defendant actually engaged in a "to be or not to be" decision -- to be a felon or not to be a felon, to step over a clear line that separates criminality from sin. There is no reason to believe that John Edwards ever made that decision, because the law governing his conduct is vague, subjective and unclear in the extreme.
At the time of the founding of our republic, there was a common expression that said that a criminal law must be so clear that a potential defendant "can read it while running and still understand it." The law under which Edwards was tried was so unclear that a bevy of lawyers could not understand it while sitting and studying it for hours.
So let the remaining charges be dropped against John Edwards. Let him be relegated to his deserved place in history, and let us reserve the criminal law for real felons who knowingly violate clear criminal statutes. If Congress wants to criminalize what Edwards was accused of doing, let it enact a clear law that gives fair warning to all politicians that they may not accept any gifts, regardless of intent. I doubt Congress will pass such a law.
The opinions expressed in this commentary are solely those of Alan Dershowitz.