The study challenges the widespread assumption that the decision rule of 'consensus', whereby decisions are made by 'tacit consent', i.e. without voting and through the absence of open dissent, attributes veto power to each decision-maker. It addresses this assumption from a conceptual, an analytical and an empirical point of view and reassesses the democratic value of this decision rule and its empirical applicability in this light.The main argument of the study is that veto options are restricted in so many ways under the rule of consensus that this general assumption is misleading. It is shown that the power to veto collective decisions under consensus rule is severely limited by various social mechanisms and norms, that it is furthermore asymmetrically distributed amongst decision-makers and additionally de-activated in a large share of empirical cases by an effective 'shadow of majority voting'.A comprehensive assessment of input-and output-related dimensions of democratic legitimacy shows how the equality of participation and of influence and the norms of transparency and accountability are violated by the restricted veto options and by the ambiguous preference order that follows from the peculiar logic of this decision rule, while the rule's efficiency is striking and group commitment is typically not lower than under voting rules. Considering strengths and weaknesses of the decision rule, its suitability in various political contexts is discussed.Key words : consensus, collective decision-making, tacit consent, veto power, democratic legitimacy.Cette étude discute l'hypothèse courante selon laquelle la règle de décision par consensus, par laquelle les décisions sont prises par « consentement tacite », c'est-à-dire sans vote et en absence d'une dissidence ouverte, attribue un pouvoir de veto à chaque décideur.
IntroductionCollective decisions are very often generated by use of a decision rule that differs substantially from the unanimity rule of full, active group consent: with all kinds of empirical variations, political organisations as diverse as intergovernmental organs (e.g. This contribution challenges the assumption of individual and effective veto power under consensus rule and reassesses the rule's democratic value in this light. It argues that veto options under consensus rule are generally de-activated in "the shadow of majority voting", that the power to effectively veto is furthermore unequally distributed and that its use is generally restricted in various ways through social norms that serve to stabilise efficient consensus arenas (section 3). These arguments are embedded into an analysis of the logics of rule enforcement that provide the background for understanding social dynamics of consensual decision-making (section 2) and a discussion of the normative effects of restricted veto powers from a perspective of democratic legitimacy (section 4). In the conclusion, the findings' implications are discussed. To start with, I provide some background on the mode of consensual decision-making t...