The attorney general of Manitoba warned last March that his province's lack of opposition to the Royal baby bill is "not in any way a precedent" for future constitutional changes.

"In our view, alterations to the constitutional and legal framework of our nation require consultation with and participation by provinces and territories that is timely and meaningful," wrote Andrew Swan in a submission to the Senate committee studying Bill C-53, which changes the rules for the royal line of succession.

The bill, which became law earlier this spring, allows first-born girls to inherit the throne regardless of whether or not they have a younger brother. The changes also alter rules around marriage for individuals in the royal line of succession, including removing the prohibition on marrying a Roman Catholic.

The Harper government's legislation falls into line with changes approved in principle by leaders from the 16 countries where Queen Elizabeth is the head of state at the Commonwealth Heads of Government meeting in October 2011.

But constitutional experts continue to disagree on whether C-53 should have required the unanimous consent of provincial governments because it represents a constitutional amendment to the "office of the Queen."

The way the bill was drafted was also controversial – it does not spell out the changes Canada is making as a sovereign country but merely assents to British legislation that changes the rules that ultimately apply to Canada's monarch.

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"No constitutional amendment is required for Canada to give its assent to this U.K. legislation," repeated Julie DiMambro, a spokesperson for Justice Minister Rob Nicholson, on Monday.

C-53's road from introduction to approval was swift – the House of Commons approved it through all stages in one go, mere days after it was first tabled on Jan. 31.

On the day of its introduction, Heritage Minister James Moore, speaking to reporters on behalf of the government, was asked why the federal government had not contacted provinces to consult on the changes.

"Our government signalled back in 2011 that we were planning to make these changes," Moore said. "We've heard no opposition from any of Canada's provinces ... or any of the parties here in Parliament."

"They're free to speak. In over a year, none of them have spoken," Moore said.

Manitoba only province to express concern

Substantive review for C-53 was left to senators.

The rules of the Senate suggest that as a general policy, Senate committees reviewing legislation in which "a province or territory has a special interest, alone or with other provinces and territories" should invite those provinces and territories to make written submissions or appear as witnesses.

While not required, it is routine for this committee to decide to contact provinces and territories on such matters.

The clerk of the Senate's legal and constitutional affairs committee contacted provincial governments in early March, before the committee held hearings to hear from a handful of expert witnesses later in the month.

Manitoba was the only province that responded, writing in its submission that it "does not have any opposition to the substantive changes contained in Bill C-53."

However, Swan's letter does express concern that the deadline suggested by the committee gave provinces less than a week to consider and comment on the issue.

"Our response in this matter is not in any way a precedent for the process to be followed should other circumstances arise in the future," Manitoba's attorney general cautioned.

Canada agreed before British law passed

Notwithstanding some of the concerns that were expressed, the Senate passed the bill and it received royal assent on March 27, nearly a month before the British legislation to which it assented had cleared all its legislative stages and amendments in the U.K.

Earlier this month, two Quebec legal scholars, supported by other experts across Canada, launched a legal challenge to the bill that they're prepared to argue all the way to the Supreme Court, if necessary.

While they don't disagree with changing the rules for the royal line of succession, they object to the process the federal government used and the precedent they believe it sets.

The federal justice minister has indicated the federal government will defend its law and may decide next month to skip hearings in Quebec Superior Court and refer the constitutional question directly to Canada's Supreme Court justices.

The timing of these legal proceedings is not subject to any particular urgency with the approaching birth of the Duke and Duchess of Cambridge's first child, also next month.

Even if Prince William and Catherine's first child is a girl, all 16 countries have agreed to back-date the changes effective to when the Commonwealth leaders first agreed to the reforms in 2011.