Law is the set of rules that a country or community recognizes as regulating the actions of its people. It can include statutes, decrees and regulations issued by the executive branch of government; rules based on precedent established by courts (common law); and agreements between private individuals.

In a nation, the law can serve to keep the peace, maintain the status quo, preserve individual rights, protect minorities against majorities, promote social justice, and provide for orderly social change. Some legal systems serve these purposes better than others.

The common law system is distinguished from statutory laws and regulatory enactments by the doctrine of precedent, or “stare decisis,” which binds lower courts to future decisions created by higher ones to assure that similar cases reach the same results. This principle, which is also known as the rule of law, was developed by philosophers such as John Locke and Montesquieu.

Case law, a term that is used interchangeably with common law, refers to the collection of judicial precedents and legal authority set by previous decisions on a particular issue or topic. The authority of a case may differ from jurisdiction to jurisdiction, depending on how old the decision is and whether it is binding or persuasive.

Courts have the power to interpret and apply the laws that have been passed by the legislative branch of government. They also have the power to interpret and apply federal and state constitutional laws. The court system varies from state to state, but generally includes trial courts (District Courts) and appellate courts (Court of Appeals). There is also a highest court called the Supreme Court in each state.