Queensland is holding an inquiry into a bill whose guts says:
72A Vacating seats of members if change of political status
�(1) A member�s seat in the Assembly also becomes vacant if�
(a) for a member who was elected as the candidate of a political party�the member resigns as a member of the party or becomes a member of another political party; or
(b) for a member who was elected as an independent member�the
member becomes a member of a political party.
The federal constitution has a provision like this at S15 which says that a senator must be replaced by a member of the same political party. If Meg Lees, for instance, left the Senate she would have to be replaced by a Democrat.
The Queensland bill is a good idea. When Senator Lees accepted the Democrat nomination she agreed to resign if she left the party. I can't see any real reason why members of either house should retain their seats if they break the contract with their electors that they made by running on a party ticket. Pauline Hanson, elected as a Liberal but sitting as herself, would also have had to face a by-election. In Australia's early history MPs had to face a by-election if they accepted ministerial office.
This is 2003 and Australians vote by large majorities for party candidates. Much of the more famous skullduggery in our history, like the Field affair and the Colston affair, would have been prevented by this rule.