To be compensatory implies somehow equal to the damage caused, which is not the situation in the Tenenbaum case (over 32,000 times the wholesale price per song). If the 5th amendment limits "excessive" punishment by the government, then the government can't make laws that effect excessive punishment by legislating statutory damages to civil courts, in which the defendant has far fewer legal protections than in criminal courts. That is, if it's unconstitutional for the government to do it to you, then it's unconstitutional for the government to enact a statute letting the RIAA do it to you. Even ignoring the 5th amendment, such excessive verdicts are inconsistent with established common law precedent. Remember, the purpose of the civil court system is to find equitable remedies for wrongs. I would add that even if the statutory damages in copyright are not intended to be punitive, in reality they are punitive.