Lev I really believe you have that backwards (or the reality doesn't support those assertions). You see, the Australian government with the support of both sides of politics as recently as 2004 or so, REWROTE part of the constitution to exclude gay people, from marriage. Until that point in time, the Constitution did not specify gender for marriage and hence was open. These discriminatory changes happened due to political whim of the time.

Steel,

Actually the example you give is an excellent example on why rights need to be entrenched in the Constitution rather than by legislation. Thank you for providing this example.

The fact is the Constitution was not rewritten at all. Changing the Australian Constitution requires a referendum supported by a majority of voters in a majority of states after being passed by an absolute majority in both houses of Federal Parliament (cf., Chapter VIII of the Australian Constitution).

What occurred was that the Constitution is silent on defining a marriage (cf., Section 51(xxi)) and indeed gives power to the Parliament of Australia to make laws with respect to marriage. Thus the political opportunity existed to define marriage according as per Ruddock's Marriage Legislation Amendment Bill (October 2004).

The Constitution was not changed. The law was changed.

If the Australian Constitution had a specified a non-discrimination clause on such matters the Amendment would have been rejected by the High Court.

The reality is that when rights are entrenched in a Constitution that they are more permanent that when they are not. I can provide countless examples of this from States that have entrenched rights, if you so desire.