I'm aware of the challenge to the validity of Justice Marc Nadon's appointment to the Supreme Court of Canada, but I've been unable to find out what the grounds for that challenge are. Does anyone know?
Section 6 of the Supreme Court Act requires that 3 of the 9 justices must have served as a justice of the Quebec Superior Court, the Quebec Court of Appeal, or have been a lawyer in Quebec for 10 years.
At least three of the judges shall be appointed from among the judges of the Court of Appeal or of the Superior Court of the Province of Quebec or from among the advocates of that Province.
Ostensibly, this is because Quebec's courts use civil Law, rather than common law as is used in the rest of the country, so justices familiar with that system are needed.
Unwritten convention further dictates that of the remaining 6 justices, 3 of them are from Ontario, 1 from British Columbia, 1 from the prairie provinces (Alberta, Manitoba, and Saskatchewan), and the last from the Atlantic provinces (New Brunswick, Prince Edward Island, Nova Scotia, and Newfoundland and Labrador).
The justice he is replacing, Morris Fish, is one of the Quebec justices. He served on the Quebec Court of Appeal from 1989 until 2003, when he was appointed to the Supreme Court, so Nadon also has to be from Quebec to be able to replace him.
The challenge is regarding whether Nadon is "from Quebec" for the purpose of that law. He was born in Quebec, obtained his law degree in Quebec (from the Université de Sherbrooke), and was a member of the Barreau du Québec for 19 years, but he primarily practised law in England prior to his appointment to the Federal Court of Canada and then to the Federal Court of Appeal and he never served on a Quebec court.