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Institutions and Legislative Consensus in National Parliaments


This study focuses on how political institutions--electoral systems and legislative rules, and coalition agreement policy pledges--affect consensus in national parliaments. Two theoretical propositions are established and tested empirically. Proposition 1 contends that consensus will be higher under proportional systems of representation (PR) than under its majoritarian alternatives. Proposition 2 contends that under coalition government, legislative consensus should be higher on legislative motions lacking governing coalition commitment. Proposition 1 is tested with new legislative vote data from New Zealand and Belgium covering those countries' institutional transformations to PR. To test Proposition 2, I focus on periods of coalition government in New Zealand and Belgium after their transition to PR, and in Britain during the Conservative-Liberal Democrat coalition government.

The analysis indicates that New Zealand's electoral system change in the mid-1990s caused a significant increase in consensus, and after reform bills assigned to a select committee chaired by an opposition MP were more likely to result in a bipartisan vote outcome, consistent with Proposition 1. Belgium's institutional transformation from 1893 to 1921 coincided with a decrease in consensus on budgetary legislation. This development suggests that PR will not have a consensus inducing effect in the near-term if the adoption of PR coincides with democratization, though the adoption of PR sets the stage for consensus building over time.

Support for Proposition 2 is mixed. In post-reform New Zealand I find that confidence and supply agreements hold those parties to the agreement together when the corresponding bill comes up for a final vote. However, governing coalition commitments are not found to increase consensus in New Zealand. During the Catholic-Liberal coalition government in Belgium from 1921-23, the opposition Socialist Party was significantly more likely to oppose the government on votes approving bills prioritized in the government's post-election declaratory speech, consistent with Proposition 2. During the Conservative-Liberal Democrat coalition in Britain, government policy commitments have a limited effect on vote outcomes. This finding confirms that the effect of coalition agreements on legislative voting in an otherwise majoritarian parliamentary system will be limited.

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