Immergut (1990, 1992b) characterizes political systems in terms of their ‘‘veto
points’’ which are formed by the combination of constitutional rules and political
majorities at any given point in time. A ‘‘veto point’’ is deWned as a political arena
with the jurisdictional power to veto a government legislative proposal, in which the
probability of veto is high. This model assumes that politicians within the executive
or legislative branch have decided to propose legislation, and considers the points in
the subsequent chain of decision making in which veto is likely. Although it is
tempting to overextend this model to call any locus of political disagreement a
‘‘veto point,’’ the original intent was to present a restricted deWnition. If, for example,
a law must be passed in the two chambers of a bicameral parliament, and the second
chamber is controlled by a diVerent majority from the Wrst chamber, then disagreement
between the two chambers and hence, second chamber veto of Wrst chamber
decisions is likely. Under these conditions, the second chamber should be considered
a veto point. Other examples of potential veto points are: constitutional courts,
presidents, and referenda. In the European legislative process, the European Parliament
(EP) has only been a veto point since the co-decision procedure was introduced
by the Treaty of Maastricht (1993).