On the one hand, the Catalan crisis can be viewed from France as an unprecedented breach of the rule of law. Even if the case is very specific and even if their posture towards states’ sovereignty is not always consistent, the European leaders, in particular the French ones, strongly support the Spanish central government. On the other hand, the Catalan crisis is all the more carefully followed in France that the French decentralised unitary State has currently to face some claims for greater autonomy by two specific territorial authorities, Corsica and New Caledonia. These demands can be regarded in light of the Catalan crisis and other similar situations in Europe, but the same causes don’t always produce the same effects... I- The Catalan Crisis seen from France: An unprecedented Breach of the Rule of Law A- A Particular Cause 1- A Specific Regionalised State 2- A Singular Crisis B- The strictly legalistic approach of the European and French Leaders 1- The Strong Support for Spanish Central Government 2- The European Paradox towards States’ Sovereignty II- The claims for greater autonomy in France in light of the Catalan case: Some similar Causes but different Consequences A- France as an Indivisible Decentralised Republic 1- An Unitary State 2- The Distortions of the Principle B- The Strong but Asymmetric subnational diversity 1- The claim for Autonomy in Corsica 2- The Process of Independence in New Caledonia