Judicial preview acts as a tool to assure that no laws to be enacted conflicts with the constitution. For that reason, it is of importance that the authorities set to perform the judicial preview are independent towards the ruling power. The aim of this essay is to do a comparison between how judicial preview is done by the Council on Legislation in Sweden and by the Constitutional Council in France. The essay examines how this preview acts as a tool to guarantee the supremacy of the constitution and to insure a none confrontational legal system. This is done with the help of the method of comparative law and the legal dogmatic method. The result of the analysis shows that judicial preview plays an increasingly important role of guaranteeing the supremacy of constitutions in legal systems of increased complexity and in societies that are experiencing political tensions. The result also shows that the constitutions in both Sweden and France is increasing in importance to protect the ways of government, democracy and basic rights for the citizens. Based on the analysis the forms of judicial preview should be reviewed and stronger safeguards for the constitution may be of interest in the future.