Law is a system of rules created and enforced by social or governmental institutions to regulate behavior. Its precise definition has been a subject of longstanding debate, with some writers, such as Thomas Aquinas and William Blackstone, taking a utilitarian approach to the question, and others, such as the philosopher Jeremy Bentham, seeing it as commandments backed by the threat of sanctions issued by an authority to whom citizens have a natural propensity to obey.
Other writers on law have viewed it as a social contract, a code of ethics, or a moral philosophy, with the concept of natural laws emerging in ancient Greek thought. These have been reshaped in modern times by Max Weber and his work on the origin of law, with law often being understood as a result of the extension of state power.
Many different areas of law are considered, with civil rights and constitutional law addressing the rights of individuals to a fair trial and due process, while environmental protection and labour law address the interests of groups and citizens to clean air and water or a living wage. International law addresses the interaction of nations via treaties and agreements. Immigration law and nationality law deal with the rights of people to live in a country not their own, and to gain or lose citizenship. Criminal law addresses conduct that is harmful to society, and can lead to imprisonment or fines. Family law deals with marriage, divorce and the rights of children.