What is the Common Law? Short answer: the phrase “unwritten common law” usually refers to the body of judge-made legal principles, customs, and background rules that developed outside (or before) statutes and formal codes — the pre-existing legal fabric judges draw on to fill gaps, interpret statutes, and resolve disputes. It’s not a single book of laws but a living set of precedents, customs, maxims, and equitable principles that courts historically relied on when there was no controlling statu