How to choose a constitutional theory

People concerned about constitutional law confront a large number of competing constitutional theories, which offer conflicting accounts of how judges should interpret and apply the Constitution. Assessment of such theories needs to be based partly on normative grounds. Moreover, there is a surprising degree of implicit agreement among constitutional theorists about the criteria that a constitutional theory ought to satisfy. Besides "fitting" either the text of the written Constitution or surrounding constitutional practice, constitutional theories should be judged based on their capacity to (i) maintain the rule of law (ii) preserve fair opportunity for political democracy, and (iii) protect a morally and politically acceptable set of substantive rights. Determining which constitutional theory would best promote these goals requires a partly instrumental calculation, including an assessment of who our judges and Justices are likely to be. Nonetheless, the need to select a theory on instrumental grounds does not justify unprincipled, case-by-case manipulation. A good constitutional theory should impose constraints on those who accept it.