Epstein argues that blackmail is illegal because the blackmailer participates in the concealment of information, may offer additional aid and advice on how to conceal information, and may induce the blackmail victim to commit crimes to raise blackmail payments. Epstein's theory does not explain what is wrong with aiding, compounding, or participating in concealment or why blackmail is particularly likely to induce thieving behavior by the victim. Thus, Epstein's theory does not distinguish blackmail from legitimate activities such as negotiating, buying goods, settling embarrassing lawsuits, concealing information, and counseling others to conceal information. The harmful quality of the blackmail act that justifies its being outlawed is the blackmailer's use of leverage that is not properly his for personal advantage. The leverage against the blackmail victim properly belongs to the police (in the event of a crime) or to a third party whose interests would be directly served by the revealing of embarrassing or advantageous information. Thus, blackmail should be illegal because threateners ought not be allowed to use other people's leverage for their own gain. Fifty-nine footnotes are provided.