In this paper I analyze the Theory of Principles developed by Humberto Ávila, and the importance of weighing up principles in administrative disciplinary and judicial proceedings in order to resolve any conflicts. To this end, this work was structured firstly with a summary of the theory addressed, and later the opinion of other authors of administrative law on the same subject was collated. Examples were provided by case law from the Brazilian Supreme Courts, where it was possible to identify some issues in which misinterpretations were made by the legal operators directly involved in the cases in their daily lives. It was found that, faced with the challenge of identifying the concepts of normative species, once making the correct distinction between principles and rules, the evolution of the Law brings new horizons, since the boundaries between normative species can be tenuous when they refer to fundamental rights.