 The main problem with both ad hoc and rule-based policy tests does not lie with their “functionalist” approach (Cohen 1935; 1937). to legal concepts such as causation, for we should always ask after the purpose of the rule or institution in which a concept figures in order to ascertain its legal meaning. Yet for anyone who thinks that criminal law and torts have dominant, justice-oriented purposes, the open-endedness of these policy tests will be disqualifying. If retributive justice is the value served by criminal law, and if such justice requires that we grade punishment proportionately to causation, then criminal law’s proximate cause tests should aid in finding when offenders really cause a harm. Analogously, a tort law that uses causation to mark out those owing duties of corrective justice will limit those owing such duties of compensation to those who have really caused the harms for which compensation is sought. On such a view of tort law, proximate causation should aid in separating those who really have caused a harm from those who have not. To serve both retributive and corrective justice, thus, the last thing one wants to do is to define legal causation so that the label names a balance of values rather than the factual state of affairs (real causation) that determines moral blameworthiness. The Legal Realists’ explicit policy tests are anathema to any justice-oriented scheme of punishment or of compensation.