We are all institutionalists today; we all think law is produced and applied by its own institutions. The essay reconstructs the metamorphosis of this idea from one of its founding fathers, Santi Romano, through Herbert Hart’s theory
of institutionalization, up to Neil MacCormick’s neo-institutionalism. In the § 2, the Romano’s classic institutionalism is interpreted as a positivist and a pluralist stance, but not as a realist one. In the § 3, then, the Hart’s wellknown
typology of power-conferring rules is re-read as a theory of the institutionalization of law, in terms of juridictional, legislative and constitutional states. In the § 4, finally, MacCormick neo-institutionalism is depicted as a full and more sophisticated philosophy of law, with ontological, phenomenological and deontological features. The institutionalism, however, needs a distinctive criterion between legal and non-legal institutions. The conclusion proposes the criterion of justice, but only in the modest sense of adjudication.
