Law is a set of rules that form a framework to ensure a peaceful society. It is enforced by governmental institutions, and if it is broken sanctions can be imposed. It is not easy to give a precise definition of law, since legal systems differ, and individuals have many different views about what it should consist of. However, some important theories about law can be outlined.

Traditionally, law has been understood as an immanent system of social restrictions that regulate human behavior and provide for the protection of people’s property rights. A common feature of laws is that they contain a number of specific prohibitions and rewards. For example, a criminal offense such as murder requires a specific intent to commit the crime. It is not sufficient to show that an individual had a desire to kill; the person must have actually intended to carry out the act of killing, even if the intention was not carried out in this particular case.

A further feature of laws is that they have to be interpreted, understood and applied by a group of experts called judges. This process is known as judicial review, and is a key part of the rule of law. In a democratic state, this process is carried out by the supreme court.

While the exact rules of law vary from country to country, there are certain fundamental principles that are common to all systems of law. In any legal system there is a hierarchy of courts that make up the judicial branch of the government, and lower courts are bound to the decisions of higher courts. There are also constitutional and legislative branches of the government, but the main function of all judicial branches is to interpret the law and decide how it should be applied in individual cases.

There are many fields of law, and some are highly specialized. Space law, for example, addresses human activities in the Earth’s orbit and outer space, while labour law involves the tripartite industrial relationship between worker, employer and trade union, and concerns issues such as health and safety or a minimum wage. Tax law covers the regulations that govern value added tax, corporate tax and income tax, while banking and financial law sets the minimum standards of capital banks must hold, and rules about best practice for investment.

Despite the complexity of law, some broad ideas about what it should comprise are shared by most legal scholars. These include the principle that the content of law should not comprise precepts that are either unattainable or force people to do things which exceed their capabilities. The fact that there are no means of empirically verifying the contents of law, therefore, makes it impossible to prove whether a particular body of law is correct or not. For more detailed expositions of the various fields of law see aviation law; bankruptcy law; cartography; business law; civil procedure; contract law; constitutional law; criminal law; family law; inheritance law; maritime law; medical jurisprudence; property law; and transactional law.