In everyday language , “ common law ” is often used loosely to mean customary practices or norms that people follow because “ that ʼ s how it ʼ s always done ,” even when those practices are not written in any statute or code In strict legal usage , though , common law is still law : it is judge ‑ made , precedent ‑ based rules developed through court decisions , as opposed to codified statutes or regulations passed by a legislature If you want to stay strictly in the “ practices , not law ” sense , it can help to say “ custom ,” “ usage ,” or “ social / industry norms ” rather than “ common law ,” which lawyers will hear as judge ‑ made law rather than mere practice ⁂ common law as in practices not as in law ... codified law and statutes are not common law 1 2 3 4 5 Practices vs codified rules Codified law and statutes are enacted texts ( codes , acts , regulations ) and , by definition , are not common law ; they are “ statutory ” or “ civil ” law depending on the system 2 4 Common law operates as a body of rules inferred from practice : courts look at customs , prior decisions , and social practices , then articulate legal principles that guide future cases , which is why it is sometimes described as law “ based on customs and principles of society .” 3 1 Where “ just practices ” fit in Pure social or industry practices ( e g ., how a trade usually handles delivery terms , or how neighbors customarily respect certain boundaries ) start as non ‑ legal customs : they are not law until a court or authority treats them as binding in a dispute 6 1 When courts repeatedly recognize such customs to decide cases , those practices become part of the common law of that area ( for example , trade usage influencing contract terms , or longstanding practices about property boundaries influencing rights of way ). 7 6 Clear separation from statutes Once a legislature takes those judge ‑ made or customary rules and writes them into a statute , those rules are , from that point on , statutory / codified law , even if they originated in common law or custom 5 2 So in a tight sense : “ common law ” is the layer of judge ‑ developed rules that sit alongside or underneath statutes ; “ practices ” are the raw customs and habits that may or may not ever be elevated into that body of law 2 3 1 3 https :// www silverthorneattorneys com / what - is - common - law - examples - definitions / https :// en wikipedia org / wiki / Common _ law https :// lawreview uchicago edu / online - archive / concept - common - law https :// legal thomsonreuters com / en / insights / articles / what - is - common - law https :// www law berkeley edu / wp - content / uploads /2017/11/ CommonLawCivilLawTraditions pdf https :// www illinoislegalaid org / legal - information / basic - overview - common - law https :// www lloydlawcollege edu in / blog / common - law - definition - origins - development - examples html https :// coolidgelawfirmaz com / common - law - v - statutory - law - criminal - defense - attorney / https :// www youtube com / watch ? v = JHqLUgHrWLE https :// www investopedia com / terms / c / common - law asp