Courts exercising judicial review in every state require the conflict between a statute and the state constitution to be "clear," rather than simply shown by the preponderance of the evidence. In almost every state, however, courts also require proof of unconstitutionality beyond reasonable doubt. A state-by-state canvass shows that in the great majority of states, a clarity requirement appeared first, sometimes long before a noreasonable- doubt rule. To the extent they conflict, clarity has a better pedigree, but there are compelling reasons to take early reasonable-doubt formulations as elaborations of a clarity rule, rather than a consciously higher standard. The judicial obligation to exercise judicial review only when a constitutional conflict is clear is coupled with an obligation to render constitutional requirements as clear as possible. This obligation means, at a minimum, responding to all contrary considerations with an adequate reasoned explanation, as in contemporary administrative law. Because clarity is contingent on the amount of analysis that courts have given a constitutional issue in response to litigation, it can change over time. Are historic rationales for a clarity requirement obsolete? One basic sort of rationale--the gravity of judicial review because of its resistance to correction--is not. Another sort of rationale, however--deference to the constitutional views of elected branches--is undermined if and when legislators fail to conduct constitutional analysis or executive officers fail to justify statutes adequately in litigation. Judicial consideration of such failures, however, need not eliminate a clarity requirement, which is a burden of persuasion, not production. Failures of legislative or executive justification can satisfy a clarity requirement or presumption of constitutionality rather than eliminating them. [ABSTRACT FROM AUTHOR]