Facing growing concern about another possible battle over a Supreme Court appointment, the Conservative government sought to quell controversy, saying the process for choosing the next judge has not begun. But neither Prime Minister Stephen Harper nor Justice Minister Peter MacKay expressly ruled out naming the judge in question Tuesday.

With Justice Robert Mainville appearing to some legal observers to be moved around like a chess piece to make him eligible for the Supreme Court, Opposition Leader Thomas Mulcair accused the government of planning to defy the Supreme Court. It ruled 6-1 in March that judges from the Federal Court of Appeal – Justice Mainville's court – are ineligible.

"Why is the Prime Minister starting a war with the Supreme Court?" Mr. Mulcair asked in the Commons.

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Mr. Harper replied, "There is no vacancy on the Supreme Court of Canada at the present time and there is no process under way to look for a replacement for an eventual vacancy on the Supreme Court of Canada."

Justice Louis LeBel has announced he will retire at the end of November, when he turns 75, the retirement age.

On Friday, Mr. MacKay announced that he has moved Justice Mainville to the Quebec Court of Appeal. Federal Court judges are not eligible for the three Quebec seats on the Supreme Court, and the government's choice of Justice Marc Nadon of the Federal Court of Appeal last September was blocked after a six-month fight at the Supreme Court. Rocco Galati, a Toronto lawyer who filed the initial challenge against the Nadon appointment, is also challenging Justice Mainville's appointment to the Quebec appeal court, and any subsequent appointment to the Supreme Court.

Mr. Harper said Tuesday that he intends to respect the letter and spirit of the Supreme Court's ruling in the Nadon case.

Mr. MacKay's office later sent out a statement that for the first time referred directly to Judge Mainville and his intentions: "With the permission of Justice Mainville, we are able to confirm that he expressed an interest in a transfer to the Quebec Court of Appeal for personal and professional reasons that obviously have nothing to do with an upcoming vacancy at the Supreme Court of Canada."

Justice Mainville, an expert in aboriginal law with three decades of experience in Montreal before becoming a judge, was on the government's confidential list of top candidates for the previous two Quebec appointments, sources have told The Globe.

The Quebec government also expressed concern. A spokesperson for Justice Minister Stéphanie Vallée said that while the appointment of Justice Mainville to the Supreme Court is "purely hypothetical," the province "wishes that the federal government will respect the spirit of the Supreme Court's earlier decision."

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Some legal observers in Quebec fear the government will undermine the legitimacy of the Supreme Court if it attempts to defy the spirit of the Nadon ruling.

"It's very depressing for federalists like me who are trying to make some sense of this country for our fellow citizens in Quebec," University of Montreal law professor Jean Leclair said.

"These people are thinking as politicians, not statesmen. Legality is not the only issue; legitimacy is the basic issue."

Jeremy Webber, law dean at the University of Victoria, said that there is nothing inherently wrong in a progression of appointments that prepares a judge for the Supreme Court. But many people see the appointment of Justice Mainville as improper, he said, because the government has lost public trust that it respects the integrity of the judicial process.