But the appointment came with a twist: Gascon won't be summoned to appear before a parliamentary committee because the selection process — under fire of late in the wake of the botched appointment of Marc Nadon — is under review.
The seat, one of three Supreme Court seats reserved for Quebec, has been vacant since the retirement last summer of Justice Morris Fish.
"Mr. Justice Gascon's wealth of legal knowledge and experience will be of significant benefit to this important Canadian institution," Harper said in a statement.
"His appointment is the result of broad consultations with prominent members of the Quebec legal community."
The high court declared in March that Nadon, the semi-retired Federal Court of Appeal judge who was Harper's original appointee, didn't meet the specific criteria for Quebec judges as spelled out in the Supreme Court Act.
Paloma Aguilar, a spokeswoman for Justice Minister Peter MacKay, said in an email late Tuesday that Gascon would not appear before a parliamentary committee — a practice first established in 2004 by the Liberal government of Paul Martin.
Aguilar said the appointment process was under review as a result of "recent leaks" — an apparent reference to a recent Globe and Mail report that disclosed details of the shortlist of candidates that included Nadon's name.
"These appointments have always been a matter for the executive and will continue to be so," Aguilar said.
"As we are concerned about recent leaks from what was intended to be a confidential process, we are reviewing the process for future appointments."
Gascon spent 10 years as a member of the Quebec Superior Court before joining the Quebec Court of Appeal in 2012.
He is a specialist in civil and commercial litigation and has lectured extensively in business and labour law in Quebec.
Quebec Justice Minister Stephanie Vallee welcomed the appointment.
"An eminent jurist," she said just a few minutes after it was made public. "I'm very happy to see that Quebec finally has its third justice on the bench."
The federal NDP also hailed the appointment.
"I don't think anyone can find anything (bad) to say," said Francoise Boivin, the party's justice critic. "He's very highly regarded."
The court, which normally consists of nine members, has been short a justice for nearly a year, the vacancy being among the three seats reserved by the Constitution for jurists from Quebec.
Aguilar said the government was under pressure to fill the vacancy, and cited the example of Justice Thomas Cromwell, who was appointed in 2008 without a selection committee or a parliamentary inquisition by MPs.
"We said we would act quickly to ensure the Supreme Court has a full complement of judges," she said. "Both the Liberal party and the NDP have repeatedly called on us to fill this seat quickly. In moving to appoint Mr. Justice Gascon, we have done precisely that."
Last month, the behind-the-scenes machinations of the appointment process bubbled to the surface, exposing an unprecedented — and ultimately very public — spat between Chief Justice Beverley McLachlin and the Prime Minister's Office.
The Conservatives suggested McLachlin inappropriately tried to make contact with Harper to discuss potential legal problems with Nadon's appointment.
The Globe report said it wasn't just Nadon that prompted McLachlin to contact the government, but a shortlist of candidates that included no fewer than four Federal Court judges, even though it was far from clear whether such candidates would be eligible.
As part of the selection process, the government stacked the deck with Federal Court candidates in hopes of nominating a more conservative judge than it believed was otherwise available in Quebec, the report suggested.
Harper disclosed the appointment Tuesday while aboard a flight to Europe, but the news wasn't released until after his plane touched down in Warsaw.
Harper will have one more Quebec vacancy on the Supreme Court to fill on Nov. 30 when Justice Louis LeBel steps down at the age of 75, after nearly 15 years on the high court.
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