Article L112-1 of the French Monetary and Financial Code
Subject to the provisions of the first paragraph of article L. 112-2 and articles L. 112-3, L. 112-3-1 and L. 112-4, automatic indexation of the prices of goods or services is prohibited. Any clause in a successively executed contract, and in particular leases and rentals of any kind, providing for a period of variation in the index greater than the period elapsing between each revision is deemed to be unwritten….