The Polarization of Legislative Party Votes: Comparative Illustrations from Denmark and Portugal

This article introduces and demonstrate the use of a ‘legislative polarisation index’. This extends a current measure of party system polarisation, as developed by Dalton (2008), and makes it possible to include legislative behaviour in the form of roll call votes into the assessment of polarisation. The article selects Denmark and Portugal to illustrate how the index works. The cases show that increased fragmentation and increased polarisation of the party system may become more moderate when parties on the political extremes become included in the legislative process.