Law is the set of rules created and enforced by social or governmental institutions to regulate behavior. Its precise definition is a matter of long-standing debate. Law encompasses a variety of disciplines including constitutional law; criminal law; tort law; labour and employment law; maritime law; property law; and tax law.
The fundamental function of laws is to govern, protect, and promote human rights and liberty. Law also serves to regulate and constrain the exercise of power by individuals or groups who command political authority. However, many legal systems fail to serve these fundamental purposes. For example, some laws are so restrictive as to effectively prohibit freedom of expression and other forms of free association; others are so authoritarian as to stifle dissent and stifle the quest for political change.
A legal system is typically based on a constitution, which establishes the supremacy of the legislature (the legislature is the branch of government that makes laws). Most jurisdictions have a judicial branch that adjudicates disputes that arise under the law. The United States, for instance, has a federal court system that consists of three branches: the Supreme Court, the Court of Appeals, and the District Courts.
Laws are written to forbid certain actions and to sanction those who break the laws by imposing fines or imprisonment. Laws can be created by a legislative body, such as Congress, which then passes the legislation to the executive branch for final approval. A law can also be made by a judicial branch, such as a court decision or an executive order. A law is often codified into a set of rules, such as the United States Code, which is arranged by subject matter.
In a law-based society, the premise is that all citizens are equal before the law. This means that the laws of a nation, state, or province apply to all citizens equally. In addition, a citizen cannot be denied the right to a fair trial by an impartial judge or prosecutor. The judiciary also plays an important role in preserving the rule of law by hearing complaints from those who feel that a law has been unfairly applied.