Concept
Party discipline is a system of political norms, rules and subsequent respective consequences for deviance that are designed to ensure the relative cohesion of members of the respective party group. In political parties specifically (often referred to as the caucus or parliamentary parties), the essential purpose of party discipline is to get all its parliamentary members to maintain the party line and vote in support of policies agreed to by a majority of the parliamentary members (or of the party leadership). In order to maintain party discipline, given political parties usually appoint a party whip whose primary task it is to maintain party discipline and to ensure the given party members support the party on the floor of the legislature. In liberal democracies, party discipline commonly refers to the control that party leaders have over their caucus members in the legislature. Party discipline is important for all systems of government that allow parties to hold political power, as it can often be a determining factor in both the practical functionality of the government, as well as the efficient function of legitimate political process. Parliamentary groups can have discipline analogous to party discipline. Breaking party discipline in both formal and informal settings may result in a number of consequences. Punishment for members who break party discipline largely varies on a case-to-case basis, but members may find themselves in a variety of positions from being internally demoted in the party to being expelled from the party itself. This results in there often being immense pressure for parliamentarians to compromise their beliefs if they conflict with the policy or decision that has been made by the parties leadership. In order to maintain strict discipline and discourage behaviour such as floor crossing, which entails the given member leaving the party to join another caucus in the legislature, parties often offer a number of incentives to loyal members.