 The sixth and final modification of the counterfactual test of cause in fact is motivated by the proof problem. Particularly in criminal cases (where one has to prove causation “beyond a reasonable doubt”) it is often impossible to prove that the harm would not have happened but for the defendant’s act. What courts in effect adopt is a “lost chance” approach to counterfactuals. On this modified test, one does not ask whether the act was necessary to the harm actually occurring; rather, one asks only whether the act was necessary to the harm having the chance of occurring that it did (Lewis 1986). This is a “necessary to chance (of harm)” sort of test, not a “necessary to harm” test (Johnson 2005).