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Boston University School of Law




Ignorance of the law is generally no excuse. I say generally because the century since the publication of The Path of the Law has brought a small but increasing number of exceptions to the rule. In Oliver Wendell Holmes's day, however, exceptions to the rule were nearly nonexistent, much to Holmes's satisfaction.1 In The Common Law, Holmes said that the law requires persons "at their peril to know the teachings of common experience, just as it requires them to know the law." 2 He did not, of course, actually think that common experience was perfectly knowable or judicial interpretation perfectly predictable, but that did not undercut for him the authority of the judge to require that persons know and obey. 3 Holmes's firmness on this matter and his subsequent characterization of law as prediction in The Path of the Law imply further that judges must require everyone to know the mechanisms and categories of legal prediction, as well as those lessons of economics and other social sciences that inform the policy decisions that judges unavoidably make when they make and apply the law. 4 All of the considerations that ultimately influence a court in its statement of a legal rule are in fact the very law that every person is required to know and obey, even amid an indeterminacy recognized by Holmes more than a century ago and since elaborated upon by so many commentators.



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