Law is the set of rules that a community recognises as governing its members. The term can also refer to the legal system itself, which includes not only the laws themselves but also the structure and operation of the judicial and executive branches of government. Law is a broad subject, covering everything from criminal and property law to international, constitutional and human rights law.
There are several specialised fields of law, such as immigration and nationality; family law; and employment and labour law. Other areas include criminology, taxation and corporate law. The study of law is often regarded as part of the social sciences, and it intersects with many other disciplines, including philosophy (often in the form of natural justice); ethics; sociology; and history.
The development of law is closely linked with the evolution of societies and culture. In pre-modern times, societies usually relied on customary law and oral traditions as the basis of their legal systems. However, during the Roman Empire and medieval Europe, a system of formal written law developed. In addition, scholarly work on ancient and medieval legal thought led to the creation of the first modern legal codes.
A key feature of contemporary law is that it is not merely a collection of statements made by judges, but a living, evolving process that changes as society evolves. This is partly a result of the fact that the laws of nature and the human mind cannot be perfectly codified or written down. The development of modern law is also influenced by the growth of economic and technological power, which has created new legal challenges.
In the United States, where most people live, the law is mainly a product of the common law system. The common law system relies on decisions made by lower courts in a particular case, which are then used to help decide future cases with similar facts or issues. This is known as binding precedent or stare decisis.
Other countries have a civil law system, which bases its laws on statutes and regulations adopted through the legislative process. Historically, religious law played a large role in some civil law jurisdictions, and this remains the case in some Islamic communities, which use Shariah as their main source of law.
The study of law is sometimes referred to as jurisprudence, and lawyers are called prosecutors, advocates or solicitors, depending on the country. The profession is usually regulated by the government or by an independent regulating body such as a bar council or law society. Modern lawyers achieve a distinct professional identity through specified legal procedures and are usually qualified with a Bachelor of Laws or a Juris Doctor degree. Other degrees are also available, such as a Master of Laws or a Master of Legal Studies. Other titles of respect are Esquire, to indicate that the holder is a barrister; and Doctor of Laws, to denote a person who has obtained a PhD in Law.