An amendment to the Constitution Act 1907 was passed to require a referendum before the Legislative Council could be scrapped, and that this provision cold only be removed by referendum.
A new govt took office and passed bills to abolish the need for referendum and to abolish the Legislative Council.
An injunction was granted to prevent the governor-general from giving his signature to the bills before a referendum was held.
The Privy Council upheld this injunction, since parliament was free to bind itself and therefore the conditions governing the initial law were valid.