At the 2011 Commonwealth Heads of Government Meeting (CHOGM) in Perth, the 16 States with Queen Elizabeth II as Head of State agreed to modernise the laws of royal succession.
English common law currently provides for the Sovereign's oldest son to succeed to the Crown. Only where the Sovereign has no son does a daughter succeed. Further, the Bill of Rights Act 1689 and the Act of Settlement 1701 prevent anyone married to a Roman Catholic from succeeding to the Crown. By way of the Constitution Act 1986 and the Imperial Laws Application Act 1988, this is also the law of the New Zealand.
The realm governments instead propose that succession be genderneutral and based only on order of birth. They also propose that marriage to a Roman Catholic not preclude succession.
Additionally, realm governments propose repealing the Royal Marriages Act 1772. This requires all descendants of King George II (who reigned from 17271760) to obtain the Sovereign's permission before marrying. Proposals would limit this requirement to the first six in line to the throne. For them, failure to obtain the Sovereign's permission would make them ineligible to succeed to the throne, but not invalidate the marriage.
New Zealand's Cabinet Office is coordinating discussions amongst the realms as to how and when these changes are implemented. This will vary from realm to realm. In New Zealand (as in Great Britain) legislative amendment will be required.