Vetospieler

Vetospieler, in political science often translated as veto player, denotes an individual or collective actor whose consent is necessary to change public policy. The concept was developed by George Tsebelis in his 2002 work Veto Players: How Political Institutions Work and is used to explain why some systems resist major policy change while others move more easily. A vetospieler can be an institution—such as a president with a veto, a prime minister and cabinet, a legislature, or a constitutional court—or an organized political actor outside the formal government, like a political party or a coalition partner, that has the power to block proposals.

Policy change requires forming a coalition of veto players whose combined positions support the new policy and cross the relevant thresholds. The set of veto players and the location of their policy preferences along a continuum determine how large a reform must be to secure approval. The more veto players exist and the more dispersed their preferences, the harder it is to change policy, leading to greater policy stability; conversely, fewer veto players or more aligned preferences facilitate change.

Veto players are used to compare political systems, assess constitutional design, and explain variation in policy outcomes across countries and over time. Tsebelis distinguishes institutional veto players (formal authorities whose approval is required) from non-institutional veto players (informal or external actors). Critics note that the model assumes relatively stable preferences and clearly defined veto thresholds, and may simplify complex political bargaining. Nonetheless, the concept remains a central tool in institutional analysis and comparative politics.