Law is a system of rules and regulations that governs the behavior of individuals and groups in a society. Its purpose is to promote order, stability, and justice by providing a framework for resolving disputes and preventing harm. In addition to setting standards and maintaining order, laws also protect individual liberties and rights, preserve property, and advance social change. Laws are made by governmental institutions and other authorised bodies, which impose them on members of society to regulate their activities and control their behaviour. The concept of law has many different facets, and the study of law encompasses a wide range of subjects, including legal philosophy; constitutional law; administrative law; criminal law; family law; property law; and tort law.
Throughout history, legal systems have evolved to meet the needs of specific societies. For example, Roman law was heavily influenced by Greek philosophy and underwent major codification during the reigns of Theodosius II and Justinian I. In medieval Europe, royal courts developed a body of case law that eventually became common law. These and other developments resulted in a rich diversity of legal practice around the world.
Modern legal systems generally fall into one of two categories: civil law or common law. In “civil law” jurisdictions, legislatures adopt statutes and regulations. In contrast, judges or barristers in “common law” systems write their decisions as precedent that binds future courts to reach similar conclusions. This principle, called stare decisis (Latin for “to stand by decisions”), is the foundation of the rule of law.
In many jurisdictions, the underlying principles of common law are further defined by a body of caselaw and custom that a judge or barrister must consider in making their decision in a particular case. The rules of evidence — what can and cannot be admitted in court — are another important part of the caselaw.
In addition to formal sources of law, a judge or barrister may use persuasive or “soft” factors when making a decision. These include societal conventions, morality, equity, justice, and professional opinions. A judge or barrister may also be influenced by the factual circumstances of a case or the views of other judges. In some countries, the judicial system includes special officers who screen applicants for pretrial release and monitor convicted defendants released under supervision. These are known as probation officers or pretrial services officers. Other specialised personnel in the judiciary include prosecutors, public defenders, and lawyers who represent defendants who can’t afford their own private attorneys in criminal cases (“in forma pauperis”).