This volume analyzes the evolution of the main elements of administrative procedures through a methodology that overcomes the established observations within each legal tradition. The author identifies the role played by subjective legal positions in the formation of the rules on procedures, and examines the primary characteristics thereof. The analysis is carried out through preliminary methodological clarifications based on the notion that the strength with which the principles have established themselves in the national and international legal systems is a key factor. The author reconstructs the systems which tackles and resolves the problems of administrative inertia and the limits that the individual juridical experiences impose on the discretionary power. He also identifies procedural models and their diffusion in comparative law.