In law, common law (also known as judicial precedent or judge-made law, or case law) is that body of law derived from judicial decisions of courts and similar tribunals.
The defining characteristic of “common law” is that it arises as precedent. In cases where the parties disagree on what the law is, a common law court looks to past precedential decisions of relevant courts, and analyses the principles of those past cases as applicable to the current facts.
If a similar dispute has been resolved in the past, the court will usually, follow the reasoning used in the prior decision a principle known as stare decisis.
How ever, if the court finds that the current dispute is fundamentally distinct from all previous cases known as Case of first impression” , and legislative statutes are either silent or ambiguous on the question, judges have the authority and duty to resolve the issue (one party or the other has to win, and on disagreements of law, judges make that decision)