Abstract: Those who commit real crimes should be prosecuted and appropriately punished. But the question of what kind of conduct is deserving of criminal punishment has become increasingly muddled in federal law. Although numerous ridiculous crimes that punish relatively trivial wrongs have crept into federal law, the greater danger comes from serious laws that are vague and overbroad. Further, Congress has authorized federal agencies to create tens of thousands of additional crimes that trap Americans by punishing obscure conduct. Federal agencies and prosecutors with inadequate oversight make overly aggressive application of these laws to target Americans who are often unaware...