Prince William and Kate's first child, who is due to be born in July, may not be able to inherit the throne because of a legal challenge in Canada.
Britain's efforts to change the law of succession across the 16 Commonwealth countries, where the Queen is head of state, could now be thrown into frenzy as a firstborn girl could lose the right to succession to a younger brother, if the challenge succeed, the Daily Express reported.
The changes to the law brought about by the Coalition had been agreed by all 16 of the Queen's realms, led by Britain, Canada, Australia and New Zealand.
However, professors Genevieve Motard and Patrick Taillon, constitutional experts at Laval University in Quebec City, lodged a case in the city's Superior Court on Friday, alleging that the Canadian government acted unconstitutionally by failing to seek the approval of each of the country's 10 provinces before agreeing to the changes.
They also say that the new succession laws would still prevent a Catholic or other non-Anglican from becoming the monarch, in breach of Canada's Charter of Rights and Freedoms.
The case, which is expected to take between six months and five years to resolve, threatens to interrupt efforts by Commonwealth leaders to change to the law quickly.
