Abstract
The analysis of practice and of case-law shows that, independent of the existence or not of a legal instrument, certain obligations the contents of which have not been made in writing and which do not fall under the category of imposed obligations are binding on the parties. The identification of a double condition of qualification shows the existence of a specific obligational category which, not having been envisaged as such by positive law, calls for analysis.The analysis of their exteriorisation proves to be necessary in order to understand not only the way they function but also the foundations of their enforceability. Some, qualified as non-materialized obligations by explicit reference, are identified by the stipulation, by the parties, of a clause by reference in the instrumentum which expressly refers to their enforceability. If their binding nature is, therefore, justified by the binding nature of the contract in which the contractual stipulation is provided, the contents binding vis-à-vis the contractual relationship is not, however, transcribed in the main instrument in writing. The others, qualified as non-materialized obligations by implicit reference, are those which are binding on the contracting parties without the latter justifying any explicit wish to comply with them. If this definition is similar to that of imposed obligations in that they are not necessarily expressly bound to the common intention of the parties, these non-materialized obligations can be distinguished by their foundation. Whereas imposed obligations are justified by the letter or the carrying out of a legal provision, non-materialized obligations by implicit reference can be explained by the notion of utility. The revelation of non-materialized obligations in contracts can be linked to a practical interest as, at the end of this process, a certain visibility concerning their effects enables both the shortcomings caused by their binding nature and hence the seemingly appropriate solutions to apply to be identified. The nature and the importance of the difficulties revealed justify, therefore, the necessity of setting up legal treatment, but also, of identifying the elements indispensable to find a proposition adapted to them. It can be seen that the insufficiencies related to the binding nature of non-materialized obligations are not specific to them in that they can, because of their general nature, be found in other contractual situations. The ways of treating this put forward in this study can therefore be applied to all contractual matters.