Complex sentence: These aspects to the relationship were formalised by the Statute of Westminster in 1931, which applied to Canada without the need for ratification, but Australia, New Zealand, and Newfoundland had to ratify the statute for it to take effect.
Split into simpler sentences: These aspects to the relationship were formalised by the Statute of Westminster in 1931. The statute applied to Canada without the need for ratification, but Australia, New Zealand, and Newfoundland had to ratify the statute for it to take effect.