The Constitution provides that the number of members of the House of Representatives “shall be, as nearly as practicable, twice the number of the senators” (s. 24). This not only ensures an appropriate balance between the Houses in terms of their representational roles; it also places limits on the extent to which the House of Representatives can prevail over the Senate in the event of a joint sitting following a simultaneous dissolution: essentially, a proposed law must be supported by something more than a bare majority in the House if it is to have a prospect of securing a majority in a joint sitting.
A proposal to alter the Constitution to remove this so-called nexus between the Senate and the House was rejected by the electors at referendum in 1967. The purpose of that proposal was to allow expansion of the size of the House without increasing the size of the Senate.
The Constitutional Commission of 1986-88, however, revived the proposal. The Commission’s approach recognised that the nexus plays two roles: one in regulating (but not limiting) the size of the Parliament; the other in the procedures governing a disagreement between the Houses. Other methods were proposed for containing the size of the Parliament; these would place limits on the size of the Senate without any comparable limits on the size of the House of Representatives. To address the situation arising in the case of joint sittings the Commission proposed a special majority to take account of the effect which ending the nexus would have on voting in that context.
The Commission’s analysis, however, did not include any consideration of the representational significance of the Senate, particularly its role in enabling opinion virtually excluded from the House of Representatives by the single member electorate system to be represented in Parliament. The Commission’s approach was hostile to democracy in that it showed little concern for a role in Parliament for parties or individuals enjoying significant electoral support but unable to gain representation in of the House of Representatives.
Maintaining the Senate’s capacity as a chamber broadly representative of both majority and minority electoral opinion in Australia is critical to its continuing legitimacy as a House with powers essentially equal to those of the House of Representatives, and to the role accorded to it in a joint sitting.
Another link between the two Houses is that, apart from provisions in the Constitution, electoral legislation for each House requires the support of both Houses. Thus, while in internal matters each House governs itself, elections for each House are governed by legislation. This is appropriate in a constitutional democracy.