leigh sales starting to look liberal, page-48

Yes, AND they can change THAT by act of Parliament.

This is my point. It's not set in stone, and that's precisely the point: that you cannot bind successive governments!!

You only half grasped your own point there.

The federal government has exclusive powers of taxation under s.51(ii) of the Constitution.

The legislation you refer to is nice window dressing, and it can be amended very easily indeed. It's just a provision of tax legislation.

End of story.