Corrispettività e adempimento nel sistema contrattuale romano

The research is aimed at critically reconsidering the concept of the reciprocity existing between the parties of a contract ("obligatio ultro citroque") that is intended to persist for the whole term of the contractual relationship ("sinallagma funzionale") in the emptio venditio and in the other consensual contracts producing obligations known by the prudentes (locatio conductio, societas and mandatum) and the legal institution of the exception of breach of contract which in such reciprocity finds its dogmatic basis. In the first chapter, the literary sources of law mentioning the right of the seller to keep the res vendita and those bearing witness of the faculty of the buyer to raise the exceptio mercis non traditae will be reviewed. It will be then examined the reasoning on the basis of which the legal science authors infer from the mentioned elements the existence, in the scope of the sale, of an interdependency between the obligations of the buyer by one side and of the seller by the other side also at the time of their fulfilment. In the second, third and fourth chapters an analysis of the discipline elaborated with respect to the performance of the obligations undertaken by the parties by means of lease contracts, a partnerships and a mandates will be carried on. From this analysis, the lack of any element useful to ground the theory of the sinallagma funzionale nowadays generally accepted by the authors will clearly emerge