The Professor of Law Theory, Political Philosophy and Ethics of São Paulo Law School, Ronaldo Porto Macedo Júnior, was one of the main speakers at the Colloquium ?Direito e Filosofia ? O que a filosofia tem a dizer sobre os princípios?? (Law and Philosophy - What philosophy has to say about the principles?), held in the brazilian state of Rio Grande do Sul.Macedo spoke about the theme The range and the meaning of the theory of principles in Dworkin, one of the consequences of his habilitation thesis on Ronald Dworkin. The Law philosopher from the United States used to act in the public debate and contributed his articles to the New York Review of Books - which commented decisions of the U.S. Supreme Court. The thesis turned into a book ?Do Xadrez à Cortesia ? Dworkin e a Teoria do Direito Contemporânea? (From Chess to Courtesy - Dworkin and the Contemporary Theory of Law), launched late last year by publishing house Saraiva.In February, Ronaldo Macedo also participated in an international conference on the importance of Dworkin for the Moral, Political and Legal Philosophy at the Institute of Legal Investigations of Universidad Nacional Autónoma de México (UNAM).The colloquium was held on March 17-18 at Unisinos University.