Law is a system of rules that a society or government develops to deal with crime, business agreements, and social relationships. It may be referred to as the rule of law, or natural law. It can be proved or unproven, sanctioned or unsanctioned, harmonious or antagonistic. It is a concept that is central to political philosophy, economic analysis, and sociology.
Law serves many purposes, but four main ones are establishing standards, maintaining order, resolving disputes and protecting liberties and property. It governs the activities of a nation and its people, and sets the stage for politics, economics, history and culture.
Legal systems differ widely, from those with a legislature codifying laws to those that follow the common law doctrine of stare decisis, in which court decisions are considered binding on other courts. In the latter, judges interpret and adapt existing laws to new situations through case-by-case rulings.
In the United States, federal, state, and local governments and officials set and enforce law. Judges, the president, governors, and legislatures make up a nation’s executive branch. Federal, state and local courts handle the adjudication of civil and criminal cases.
Specialized fields of law include tax law, aviation law, maritime law, space law, and environmental law. Jurisdiction refers to the geographic area over which a court has authority to hear a case. The plaintiff decides where to bring a lawsuit, but in some cases the matter can be heard simultaneously by federal and state courts of equal jurisdiction.