159In addition, it must be noted that, according to settled case-law, it is first and foremost for the party seeking to establish the Community's liability to adduce conclusive proof as to the existence or extent of the damage he alleges and to establish the causal link between that damage and the conduct complained of on the part of the Community institutions (Case C-401/96 PSomaco v Commission [1998] ECR I-2587, paragraph 71, and Case T-168/94Blackspur DIY and Others v Council and Commission [1995] ECR II-2627, paragraph 40).