A three-day Supreme Court of Canada hearing into Senate reform ended today with a presentation from two "friends of the court" appointed by the justices to give them impartial advice, followed by a brief final submission from the federal government.

In a previously filed written submission, Daniel Jutras and John Hunter agreed that abolition of the Senate would require unanimous consent of the provinces, and term limits would require 7/50 approval, that is, the approval of seven provinces representing 50 per cent of the population.

They were commenting on a government question put to the court on what kind of provincial consent would be needed to abolish the upper chamber.

The federal government is also asking the top court for an opinion on whether it can unilaterally impose term limits on senators.

It also wants to know whether it can mandate what it calls "consultative elections," meaning the prime minister would not necessarily have to name people who have won elections in their provinces to the Senate, but that he must "consider" people who have won electoral contests.

Although the government's current position is not one of Senate abolition, Prime Minister Stephen Harper has said repeatedly that the Senate must be reformed, and if not, abolished.

Saskatchewan favours Senate abolition

The lawyer representing the attorney general of Saskatchewan told the top court on Wednesday that he believes the Senate can be abolished, using the 7/50 formula.

​​Graeme Mitchell said Saskatchewan agrees with the federal government, which has made the same argument before the court.

He pointed out that just a week ago, the provincial legislature in Regina voted unanimously in favour of Senate abolition.

However, several other provinces have told the court they believe Senate abolition requires the unanimous consent of the provinces.

Mitchell argued that unanimity of the provinces is extremely difficult to achieve.

Asked by Justice Louis LeBel if the Charter of Rights and Freedoms could be amended by the 7/50 formula, and Canada turned into a dictatorship, Mitchell acknowledged that could happen, but added it would be a ''stretch" to think seven provinces would vote to deprive people of basic rights.

Alberta will also support the 7/50 formula for Senate abolition, although the province, having elected four senators, prefers an elected Senate.

Territories have no vote

The lawyers for the Northwest Territories and Nunavut argued their governments must be consulted over any Senate reforms since they have no vote in constitutional change.

Each territory has its own senator, and doesn't want to lose the seats if the Senate were to be abolished. On those grounds, their lawyers urged all 10 provinces must agree on Senate abolition, a much higher bar than the 7/50 formula.

On Tuesday, the court heard arguments from government lawyers who pointed out that a constitutional amendment of any kind requiring the agreement of all provinces has never happened.

On the same day, Ontario, Quebec, Nova Scotia, Manitoba and New Brunswick all insisted that unanimity among provinces is necessary for Senate abolition, and that the government cannot unilaterally change senators' tenure or method of selection to sit in the upper chamber.

The Supreme Court justices are expected to take six months to a year to mull over all the arguments before issuing a ruling.