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. As explained in the Court's reasons in "Reference Re Supreme Court Act, ss. 5 and 6", sitting judges of the Federal Court and Federal Court of Appeal cannot be appointed to any of Quebec's three seats. 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 rotate among themselves (although Alberta is known to cause skips in the rotation); and one from the Atlantic provinces, almost always from Nova Scotia or New Brunswick.