Statute of Limitations

Ought there be a statute of limitations on crimes?  On the one hand, the longer one goes from the time of the crime, the more the evidence loses its strength.  Over time, notoriously unreliable memories fade and become even less reliable, physical evidence decays or risks contamination, and witnesses move away.  This not only makes it tough to prosecute, but makes a fair defense much less likely.  Further, it keeps defendants from an open-ended, limitless sense of threat of suit.  If a defendant is going to bring the case, bring it.

On the other hand, it means that if you commit a crime and are good at hiding the evidence, you get away with it.  It rewards better criminals. Justice delayed may be justice denied, but justice delayed with a statute of limitations seems to deny even the possibility of justice. (Big 'ol tip of the hat to YKW for clearly framing these arguments.)

So, should there be a statute of limitations?