Abstract
The question of WHO is the ultimate constitutional interpreter poses one of the fundamental problems with which a coherent constitutional theory must come to grips. Any answer will be closely connected to other basic theoretical interrogatives, such as WHAT is the constitution and HOW should it be interpreted. Three principal theories compete here: Judicial supremacy, legislative supremacy, and departmentalism. This paper suggests a sort of analysis that transforms the question of WHO from one that yields a universally applicable response into a more complex set of queries about degrees of deference one institution owes another under varying circumstances. What emerges is a modified version of departmentalism.