Law is a system of rules created and enforced by social or governmental institutions to regulate behavior. It serves many purposes but four principal ones are establishing standards, maintaining order, resolving disputes and protecting liberties and rights. Law may be enacted through legislation or through custom and practice. A legal system may be codified, or it may be common law, civil law, or a mixture of both. The department of knowledge pertaining to these laws is called jurisprudence.
Most modern legal systems are based on civil law, but some countries have a mixed jurisdiction. In mixed legal systems, civil and common law coexist, and judges are allowed to choose the legal tradition that best suits their case. For example, some parts of the United States are governed by common law, but others are governed by state statutes and federal constitutional laws.
A key distinction between civil and common law is the way in which precedent plays a role. With common law, judges build on previous decisions to make rulings in future cases. This allows past decisions to shape the criteria that a judge uses in making a ruling, although societal changes may prompt judicial bodies to overturn outdated or biased legal traditions.
The principle of rule of law requires a society to have laws that are publicly promulgated, equally enforced and independently adjudicated. It also demands that laws be clear and accessible, and that they protect core human, property, and administrative rights. This principle is a foundation for healthy communities of justice, opportunity and peace.
In a country ruled by an authoritarian government, the law may be used to oppress minorities or political opponents. In a democracy, the law is supposed to promote social justice by providing a safe, stable environment in which people can develop their potential. This is accomplished by ensuring that all individuals face the consequences of their actions regardless of wealth or status, and that they are protected against the misuse of power by other people and the state itself.
The law is a complex and diverse set of norms, traditions, practices and policies that are instilled within a society by its various institutions and groups. Its precise definition is the subject of longstanding debate and has been described as both a science and an art. The most important elements of this set of rules are: supremacy of law, equality before the law, accountability to the law and separation of powers. These principles are necessary to maintain the stability of a society and its government and to ensure that all citizens have access to the same fundamental rules. The laws of a nation are a fundamental component of its identity, and they can shape politics, economics, history and culture in countless ways.