Reus-Smit's most significant contribution to the field is reflected in his answer to the question of the 'enigma of fundamental institutions,' laid out in 'The Moral Purpose of the State.'
"Constitutional structures are coherent ensembles of intersubjective beliefs, principles and norms that perform two functions in ordering international societies: they define what constitutes a legitimate actor entitled to all the rights and privileges of statehood: and they define the basic parameters of rightful state action."[REF] .