Rules and Principles in Legal Reasoning. A Study of Vagueness and Collisions in Artificial Intelligence and Law
Samuel Meira Brasil · Information & Communications Technology Law · 2001
There is a difference between rules and principles in Law Argumentation Theory. The conflict of rules is solved by meta-rules like Lex Superior (based in general hierarchical structure of legal system), Lex Posterior (based on later rule priority), Lex Specialis (based on specification of rules) and also by exceptions, which exclude the conflict. The collisions of rules imply the validity negation of one rule. However, this does not occur in a collision of principles. Even when one principle is not applied by collisions, its validity remains. Another point is that the priority could change, changing the overridden principle. So, it is necessary to build a reasoning model that allows reasoning with conflicting legal principles. Another problem is vagueness of principles. Vagueness does not mean just an imprecise meaning, linguistically talking. There should be attributed a semantic, or a pragmatic meaning. Vagueness of principles occurs on account of its opened antecedent, with no established conduct. In this paper a model of reasoning using Artificial Intelligence (AI) & Law methods is described aiming at treating vagueness and collisions of principles, searching to establish rationality in legal argumentation systems.