Page "Supreme Court of Canada" Paragraph 42

The Supreme Court Act limits eligibility for appointment to persons who have been judges of a superior court, or members of the bar for ten or more years.

Members of the bar or superior judiciary of Quebec, by law, must hold three of the nine positions on the Supreme Court of Canada.

This is justified on the basis that Quebec uses civil law, rather than common law, as in the rest of the country.

The 3 / 9 ratio persists even though just 24 percent of Canada's population resides in Quebec.

By convention, the remaining six positions are divided in the following manner: three from Ontario, two from the western provinces ( typically one from British Columbia and one from the prairie provinces, which in turn rotates amongst the three, although Alberta is known to cause skips in the rotation, and one from the Atlantic provinces, almost always from Nova Scotia or New Brunswick.