Equality before the law, also known as equality under the law, equality in the eyes of the law, legal equality, or legal egalitarianism, is the principle that all people must be equally protected by the law. The principle requires a systematic rule of law that observes due process to provide equal justice, and requires equal protection ensuring that no individual nor group of individuals be privileged over others by the law. Sometimes called the principle of isonomy, it arises from various philosophical questions concerning equality, fairness and justice. Equality before the law is one of the basic principles of some definitions of liberalism. It is incompatible with legal slavery.
Article 7 of the Universal Declaration of Human Rights (UDHR) states: "All are equal before the law and are entitled without any discrimination to equal protection of the law". Thus, everyone must be treated equally under the law regardless of race, gender, color, ethnicity, religion, disability, or other characteristics, without privilege, discrimination or bias. The general guarantee of equality is provided by most of the world's national constitutions, but specific implementations of this guarantee vary. For example, while many constitutions guarantee equality regardless of race, only a few mention the right to equality regardless of nationality.
The legalist philosopher Guan Zhong (720–645 BC) declared that "the monarch and his subjects no matter how great and small they are complying with the law will be the great order".
The 431 BC funeral oration of Pericles, recorded in Thucydides's History of the Peloponnesian War, includes a passage praising the equality among the free male citizens of the Athenian democracy: If we look to the laws, they afford equal justice to all in their private differences; if to social standing, advancement in public life falls to reputation for capacity, class considerations not being allowed to interfere with merit; nor again does poverty bar the way.