Law is the system of rules that a particular country or community recognises as regulating the actions of its members. It covers everything from criminal and civil procedure to property and family law. Law is an extremely wide and diverse subject, with many different theories being held about it. These theories often differ in their approach to such issues as the nature of legal systems, the relationship between the state and its citizens, and the extent to which laws should be morally based.
It is impossible to give a single, definitive definition of law, as the nature of legal systems and the reasons for them vary widely from one country to another. However, four main purposes are usually identified: establishing standards; maintaining order; resolving disputes; and protecting liberties and rights. Law is usually divided into civil and criminal law, with the former covering matters such as contract, tort and property; and the latter dealing with offences against public order, the state, the individual and society.
The relationship between law and political structures is a complex issue, which has been debated by philosophers as varied as John Austin and Jeremy Bentham. The philosopher Max Weber, for example, reshaped thinking about the extension of state power. Modern military and police power is now a key part of everyday life in many countries, posing new problems for accountability that writers such as Locke or Montesquieu could not have foreseen.
Legal systems also vary greatly between nations, reflecting their social settings and historical development. A common feature, however, is the presence of a supreme court or other judicial body that acts as the final arbiter in cases that cannot be resolved at lower levels.
Other differences are seen in the way laws are written and the manner in which they are interpreted and enforced. For example, American law has diverged significantly from its English ancestor in the substance of its substantive law and in the procedures that must be followed to bring a case before a court.
In some states, laws are codified and published in a legal code such as the United States Code, which is arranged by topic with sub-codes on specific subjects like commerce, corporations, and taxation. The Code is updated on a regular basis and is used as a reference book by judges, lawyers and other legal professionals.
Some laws are based on religious precepts, such as Jewish Halakha and Islamic Sharia, whilst others rely on further human elaboration and interpretation such as Qiyas (reasoning by analogy) and Ijma (consensus). Other types of law include aviation law, which deals with the safety standards and regulations for aircraft and is framed by national civil aviation acts, and evidence law, which defines what materials can be introduced in courts. There is even a school of law called environmental law, which focuses on the regulation and protection of natural environments. In other words, there is something called law for every conceivable situation.