'Common law' is simply judge-made law. It's law developed and honed by judges over time in their reasons for decision, case after case. It's maintained by the adherence of judges to stare decisis [Duggan v. Durham Region Non-Profit Housing Corporation (Ont CA, 2020) ]:
[52] The doctrine of stare decisis requires that all courts follow and apply authoritative precedents. ...
Born in the deep, dark depths of English feudal history and continuing it's development today, otherwise plenary common law rights apply until such time as they are removed - either: "clearly and unambiguously" by the legislature (ie. by statute), plainly in contract, or by the development over time of the common law itself.
