The Statute of Westminster gave effect to certain political resolutions passed by the Imperial Conferences of 1926 and 1930; in particular, the Balfour Declaration of 1926. The main effect was the removal of the ability of the British parliament to legislate for the Dominions, part of which also required the repeal of the Colonial Laws Validity Act 1865 in its application to the Dominions. King George V expressed his desire that the laws of royal succession be exempt from the statute's provisions, but it was determined that this would be contrary to the principles of equality set out in the Balfour Declaration. Both Canada and the Irish Free State pushed for the ability to amend the succession laws themselves and section 2(2) (allowing a Dominion to amend or repeal laws of paramount force, such as the succession laws, insofar as they are part of the law of that Dominion) was included in the Statute of Westminster at Canada's insistence. After the Statute was passed, the British parliament could no longer make laws for the Dominions, other than with the request and consent of the government of that Dominion. Before then, the Dominions had legally been self-governing colonies of the United Kingdom. However, the Statute had the effect of making them sovereign nations once they adopted it.
The Statute provides in section 4:
No Act of Parliament of the United Kingdom passed after the commencement of this Act shall extend, or be deemed to extend, to a Dominion as part of the law of that Dominion, unless it is expressly declared in that Act that that Dominion has requested, and consented to, the enactment thereof.
It also provides in section 2(1):