Constitutional law faces the challenge of integrating studies on risk and society developed in other social sciences into its research program. In a risk society, the state incorporates new regulatory functions, facing challenges related to uncertainty and scientific reflexivity. The logic of risks demands a dynamic and specialized structure for the regulation of society through law, transferring public decisions to technical bodies and courts without democratic representation and exacerbating the legitimation deficit in the state. This dissertation argues that in today s society the constitutional state becomes a risk state, characterized by taking the idea of risk as one of the main elements of definition and justification of government action. Considering the impact of contemporary risks on the justification of the state, as well as on the democratic principle, the fundamental rights and the judicialization of public policies, this dissertation proposes a constitutionally appropriate model of risk that attempts to make the political and scientific character of risk perception and assessment compatible with the necessity of using law to regulate a complex society.