Mistake or Uncertainty
SO FAR I have dealt, at every stage, with the problems of mistake on questions of fact, and with the problem of vagueness or near-meaninglessness in the "standard" for some finding-say, the finding of "not guilty by reason of insanity," or the finding of "premeditation." The picture cannot be rounded out without some attention to still another matter, one of very great difficulty-the problem which may (depending on one's legal philosophy) be thought of as the problem of "mistake of law," or the problem of "uncertainty of law."
"Questions of law" have been looked on, classically, as questions concerning the correct rule to apply to facts assumed to be known; this concept has eroded in modern time, but it will still do for a first approximation. Now in the course of criminal proceedings an enormous number