Party discipline

Party discipline is the ability of the parliamentary group of a political party to get its members to support the policies of the party leadership.

In a liberal democratic context, it usually refers to the control that party leaders have over its legislative members. Party discipline tends to be extremely strong in Westminster systems such as the United Kingdom, Canada, Australia and India in which a vote by the legislature against the government is understood to cause the government to "collapse," according to the convention of confidence votes. In these situations, it is extremely rare for a member to vote against the wishes of their party. Party leaders in such governments often have the authority to expel from the party members who violate the party line. Party discipline is much weaker in Congressional systems such as the United States Congress. In these legislatures, it is routine for members to cross party lines on a given vote, typically following the interests of their region or following other members of a borderline group within their party (for instance, the conservative Blue Dog Democrats and centrist and socially liberal Main Street Republicans).

Party discipline is usually more frequent in mass parties than in parties of notables. Thus, the French Radical-Socialist Party had no party discipline, neither did any of the right-wing parties during the Third Republic (1871-1940), to the contrary of the Socialist SFIO or the Communist Party.

The term has a somewhat different meaning in Marxist-Leninist political systems such as the People's Republic of China. In this case it refers to administrative sanctions such as fines or expulsion that the Communist Party can impose on its members for actions such as corruption or working against the party.