This isn&#x27;t to say that there aren&#x27;t ugly compromises and back-scratching going on. But it largely happens inside the parties, rather than on the floor.<p>The wikipedia article on party discipline points out that in Westminster systems, the Executive branch is formed out of the Legislative branch. Consequently, inability to control votes in Parliament literally means you are no longer in government. Most MPs greatly prefer being in government than being in opposition, so there&#x27;s another inbuilt incentive to vote the party line.<p>In Australia&#x27;s Parliament each chamber is elected on a different system. The House of Representatives is single-member electorates. This means that one of the major parties typically forms a majority that can in turn form an executive government able to pass motions of confidence and supply. In short, to govern. Only twice has this failed to occur, leaving the governing party to rely on independents to form their majority.<p>The Senate, by contrast, is formed from a multi-member scheme with an electorate per state. There are 12 senators per state, half going to the polls at election time. In practice this means the majors capture the 2 of the top 4 spots each, one of the majors captures the 5th spot, but frequently a minor party wins the 6th spot.<p>This means there&#x27;s a mix of voices in the Senate. While a lot of legislation gets passed with the agreement of the majors, for anything contentious, the government will need to negotiate with the cross-benches. Right now it&#x27;s a quite varied bunch.