When two parties are embedded in a dispute, they generally have the possibility to bargain before an external solution is imposed to them. This bargaining phase may either result from a choice of disputants to negotiate or be imposed by laws or legal contracts. The aim of this paper is to analyze the differences in terms of parties' bargaining behavior, depending upon the fact that bargaining has been imposed to them or comes from their own will. We conduct an experimental analysis in order to investigate first which kind of individuals systematically accept/refuse to bargain, and if such individuals present special characteristics (in terms of risk aversion, gender...). Then we intend to determine if a procedure in which parties are forced to bargain leads to more (less) agreements and/or a higher (lower) social gain than when parties are free whether to do so. Finally, we investigate the impact of the constraint of the behavior during bargaining for each type of individuals, in order notably to analyze whether such a constraint may crowd-out individuals' motivation to find an agreement.