Law is the system of rules a society recognises as controlling its members. It includes both the rules themselves, which are enforced by a state’s legislature, and the institutions that are involved in enforcing them. For example, a police force is a mechanism for carrying out laws, and a court is the forum where cases are heard and decisions made.
The main purposes of law are to set standards, maintain order, resolve disputes and protect liberties and rights. It is also a tool for exercising power: for example, tyrannical rulers create arbitrary laws and execute their opponents to demonstrate the rule of law’s supremacy over individuals.
Generally, laws are created by legislatures. But they can also be created by a court of justice or a tribunal. Some of the most important fields of law include contract, criminal, family and property. Criminal law covers offences against people and against private property (eg, theft). Property includes both real estate – land and what is attached to it – and personal possessions such as cars and houses. It is governed by a variety of laws including mortgages, rental agreements, licences and covenants, as well as by common law and statutes like trusts and companies.
In the United States, laws are compiled into the United States Code – which is organised by subject matter. Federal law can supersede state law in certain areas, such as aviation and railroads. But in other areas, such as antitrust and trademarks, federal law coexists with a large body of state law.