Published online by Cambridge University Press: 23 January 2015
Previous research on deregulation in industrialised countries emphasises differences between left-wing and right-wing parties, but data on product market regulation (PMR) indicate that these differences have been modest. If partisan preferences on the merits of deregulation differ sharply, why such modest differences? We argue that partisan differences only become pronounced when the government is strong and rules a relatively unified legislature. Thus, legislative fragmentation should reduce the left-right difference in PMR. We test this theory against PMR data in 29 industrialised countries, 1978–2007. We find that right-wing governments only have a strong negative effect on regulation if the legislature and the government are not fragmented.