This thesis examines the application of traditional jurisdictional doctrines to online activity. It analyses not only to what extent, and why, the Internet challenges existing principles allocating regulatory competence, but the factors which shape, and must shape, the regulatory responses to these challenges, in an attempt to create an analytical framework within which the search for viable solutions can begin. The overarching argument made in this thesis is that the keys to viable future Internet regulation are deeply embedded in past and present regulation and that we cannot simply look for the most efficient legal solutions, regardless of how they fit within existing laws. This would be inconsistent with the law's basic function to answer the need for certainty and predictability. Building upon this fundamental premise, it is further argued, and shown, that an understanding of the public law - private law dichotomy within the existing jurisdictional framework, as well as its deeply entrenched status, is essential for appreciating the severity of the jurisdictional problems caused by the Internet and actual and likely regulatory responses to them. It is argued that this explains why both sets of rules have consistently accommodated transnational online activity differently, giving rise to different problems - problems which ultimately touch upon fundamental legal notions, such as formal justice, the rule of law or obedience to law which cannot but set further outer parameters of the search for solutions to the jurisdictional problems triggered by the Internet.

Esta tese tem como objetivo investigar os limites constitucionais ao emprego de normas tributárias extrafiscais, contribuindo, de maneira original, com o desenvolvimento de métodos que possibilitem que estes instrumentos sejam controlados de modo mais preciso pelo Poder Judiciário. Para a consecução deste objetivo central, trabalhou-se a partir de quatro blocos de investigação. Primeiro, a pesquisa centrou-se em discutir a importância de segregação das normas tributárias entre fiscais e extrafiscais, analisando as diversas propostas de métodos para a separação entre estas. Ao final, a tese sugere que as normas tributárias extrafiscais devem ser identificadas a partir das suas finalidades, conforme venha a ser interpretado pelo aplicador da norma. Superada a questão, passa-se à investigação dos fundamentos constitucionais que legitimam o emprego das normas tributárias extrafiscais, quando se debate em que sentido normativo se pode falar em neutralidade tributária. Em um terceiro módulo de investigação, as normas tributárias extrafiscais são contrapostas às limitações constitucionais ao poder de tributar, ao conflito entre competência regulatória e competência tributária, ao conceito constitucional de tributo, bem como aos limites ínsitos às espécies tributárias previstas pela Constituição Federal. Por fim, apresenta-se um modelo de protocolo decisório que pode ser utilizado para fins de controlabilidade das normas tributárias extrafiscais pelo Poder Judiciário, colocando-se em destaque os princípios da igualdade e da proporcionalidade. / The main goal of this thesis is to investigate the constitutional limits on the use of non-fiscal purpose tax laws, contributing, with originality, to the development of methods that allow a more precise control of these instruments by the Judiciary Branch. To achieve such goal, the thesis was divided into four parts. The first part focuses in discussing the importance of segregation of tax laws in two groups: fiscal and non-fiscal, and analyzes the numerous methods proposed for such classification. The thesis suggests that non-fiscal purpose tax laws must be identified by their purpose, as interpreted by those responsible for applying the law. The second part investigates the constitutional basis that legitimates the use of non-fiscal purpose tax laws and discusses to what normative extent one can speak of tax neutrality. In the third part, the non-fiscal purpose tax laws are compared to the constitutional limits on taxation, to the conflict between regulatory competence and fiscal competence, to the constitutional concept of tax, as well as to the limits involving the tax species provided by the Federal Constitution. Finally, a model of decision making protocol is presented for use a mean of control by the Judiciary Branch of the non-fiscal purpose tax, highlighting the principles of equality and proportionality.