Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior. It is often described as a science and as the art of justice.
Legal systems vary considerably from nation to nation. The principal functions of law are to establish standards, maintain order, resolve disputes and protect liberties and rights. Laws may be created and enforced by a single legislative authority, resulting in statutes; by the executive through decrees and regulations; or established by judges through precedent, known as common law jurisdictions. Private individuals also create legally binding contracts and arbitration agreements that adopt alternative ways of resolving disputes to standard court litigation.
Many laws are explicitly based on religious precepts, such as Jewish Halakha and Islamic Sharia. In addition to being the basis for a legal system, these precepts can act as a guide to further human elaboration of law and jurisprudence through interpretation, Qiyas (reasoning by analogy), Ijma and precedent.
In modern societies, the extension of state power over individuals and their daily lives poses challenges to traditional understandings of the purpose of law. It is increasingly recognised that the rule of law requires, among other things: supremacy of law, equality before the law, accountability to the law, independence of the judiciary, participation in lawmaking, legal certainty and transparency, avoidance of arbitrariness and separation of powers. It is also recognised that laws should reflect the values of a democratic society.