I know that the answer to the question "What is the main topic of this text?" is in "France's highest courts are located in Paris. The Court of Cassation, the highest court in the judicial order, which reviews criminal and civil cases, is located in the Palais de Justice on the Île de la Cité, while the Conseil d'État, which provides legal advice to the executive and acts as the highest court in the administrative order, judging litigation against public bodies, is located in the Palais-Royal in the 1st arrondissement. The Constitutional Council, an advisory body with ultimate authority on the constitutionality of laws and government decrees, also meets in the Montpensier wing of the Palais Royal.". Can you tell me what it is?
France's highest courts