The parliament of New Zealand on Wednesday has modernized its royal succession law, thus finally allowing a Queen to become the country's head of state.

Passed on the third and final reading, the Royal Succession Bill effects to institute developments initially agreed by the 16 realms in 2011, who all share the Queen as head of state.

Under the revised and modernized law, the order of succession would no longer be based on gender and exclusive only to male heirs. The new bill allows an elder daughter to precede a younger son as heir to the throne. The revised and modernized law applies to children throne successors born after Oct 28, 2011. Prince George of Cambridge, who was born earlier this year, is likewise included and eligible under the law.

The new law also enables an heir married to a Roman Catholic to accede to the throne. The changes would be enforced simultaneously with the other realms. A date has yet to be agreed upon. The current queen is the elder of two daughters and had no brothers when she succeeded to the throne.

Chloe Oldfield, Vice chair of Monarchy New Zealand, welcome the passage of the bill, noting women also deserve to be heirs to the throne, and should be given equal rights in succession to the throne. She told Radio New Zealand the bill cuts out discrimination against women.

"These changes are positive for New Zealand's system of government," Justice Minister Judith Collins said.

"This Bill improves and modernises the rules of succession and helps ensure the monarchy remains relevant to our modern society."