Contractual legal liabilities, which include decennial liability, are usually one of the points that parties need to understand better, especially as regards their commencement dates. One of the main advantage of such liabilities under French law is that they shift the burden of proof of the cause of the default from the claimant to the defendant.

Whereas several recent articles have explained the principle of legal decennial liability,1 its precise commencement date is touched on but usually not defined. If the contractor cannot get to grips with it, it will never understand when its contractual liability ends, and when its post-contractual liabilities begins.

This article aims to analyse what is the commencement date of the three post contractual legal liabilities that are provided in French construction law as applied to the FIDIC Red and Yellow Books 1999 (hereafter broadly referred to as “FIDIC contracts”): do French post-contractual legal liabilities begin at the taking-over by the employer or at the date of the Performance Certificate? As the concept of post contractual liability in French law, especially decennial liability, has been developed and applied in other jurisdictions, it is important to understand not only the theory but also its application in practice.