Jacques PETIT - Professor (université Paris 2)
Gweltaz EVEILLARD - Professor (université Rennes 1)
Hélène HOEPFFNER - Professor (université Toulouse 1)
Bertrand SEILLER - Professor (université Paris 2)
Although the modification of the public contract is in principle free, it can only take place under certain limitations. In France, the rules of advertising and competition impose substantive conditions of form and procedure to determine the legality of the modifying instrument. The prohibition of agreeing to a new object, restrictions on altering the economic balance, setting financial thresholds, etc., reveal a rigorous control for any modifications. In Colombia, however, it appears that the freedom of the parties is much broader. A general threshold of fifty percent of the initial price, the possibility of altering the economics of the contract and even the fundamental modification of the object, are part of a legal system that tends to abolish all restrictions to the will of the parties regarding modification. Although it is of the essence of contract modifications to disclose the conditions initially established, a major theme is that of the nature of the change in Colombian law to reveal all the challenges of its implementation.