Commentary This is the ninth in a series of articles defending the U.S. Constitution against accusations from political “progressives.” A common accusation, especially from liberal academics and judges, is that many constitutional phrases are vague or meaningless. Or, as stated by former Supreme Court Justice William J. Brennan, they are “luminous and obscure.” Advocates of an all-powerful central government draw two lessons from their belief that constitutional clauses are vague. The first is that the document doesn’t deserve great respect because it isn’t well drafted. The second is that vagueness justifies a very wide scope for exercise of federal and judicial power. But the charge of “vagueness” is based on ignorance. The usual reason critics think constitutional phrases are vague or meaningless is that they don’t know that those phrases had specialized meanings in 18th century law. The Constitution is a legal document, and most of the framers and leading …