Common Law refers to laws formed through court decisions. The Canadian legal system is based on Common Law, which means that legal precedent – decisions made by judges in the past – influence the law (the province of Quebec has a slightly different system called Civil Law). When new cases pose legal questions, judges and lawyers refer to historical cases for guidance.
Another aspect of common law is that courts must follow the decisions of more senior courts. For example, the Supreme Court can overrule the Provincial Court. Legislation (laws passed by government) can be used to change the Common Law, or to deal with areas where the law is unclear.
For more information on Common Law, visit www.justice.gc.ca.