one who opposes bearing arms or who objects to any type of military training and service. Some conscientious objectors refuse to submit to any of the procedures of compulsory conscription. Although all objectors take their position on the basis of conscience, they may have varying religious, philosophical, or political reasons for their beliefs.

Conscientious objection to military service has existed in some form since the beginning of the Christian era and has, for the most part, been associated with religious scruples against military activities. It developed as a doctrine of the Mennonites (Mennonite) in various parts of Europe in the 16th century, of the Society of Friends in England in the 17th century, and of the Church of the Brethren and of the Dukhobors in Russia in the 18th century.

Throughout history, governments have been generally unsympathetic toward individual conscientious objectors; their refusal to under take military service has been treated like any other breach of law. There have, however, been times when certain pacifistic religious sects have been exempted. During the 19th century, Prussia exempted the Mennonites from military service in return for a military tax, and until 1874 they were exempted in Russia. Such exceptions were unusual, however.

The relatively liberal policy of the United States began in colonial Pennsylvania, whose government was controlled until 1756 by Quaker pacifists. Since the American Civil War and the enactment of the first U.S. conscript law, some form of alternative service has been granted to those unwilling to bear arms. Under the conscript laws of 1940, conscientious objector status, including some form of service unrelated to and not controlled by the military, was granted, but solely on the basis of membership in a recognized pacifistic religious sect. Objections of a philosophical, political, or personal moral nature were not considered valid reasons for refusing military service.

In Great Britain a noncombatant corps was established during World War I, but many conscientious objectors refused to belong to it. During World War II, three types of exemption could be granted: (1) unconditional; (2) conditional on the undertaking of specified civil work; (3) exemption only from combatant duties. Conscription in Great Britain ended in 1960, and in 1968 recruits were allowed discharge as conscientious objectors within six months from the date of their entry into the military.

Until the 1960s neither France nor Belgium had legal provision for conscientious objectors, although for some years in both countries growing public opinion—fortified in France by the unpopularity of the Algerian War of Independence—had forced limited recognition administratively. A French law of 1963 finally gave legal recognition to religious and philosophical objectors, providing both noncombatant and alternative civilian service with a term of service twice that of the military term. Belgium enacted a similar law in 1964, recognizing objection to all military service on religious, philosophical, and moral grounds.

Scandinavian countries recognize all types of objectors and provide both noncombatant and civilian service. In Norway and Sweden civil defense is compulsory, with no legal recognition of objection to that type of service. A Swedish law of 1966 provided complete exemption from compulsory service for Jehovah's Witnesses. In The Netherlands (Netherlands, The), religious and moral objectors are recognized. During the period of German partition (1949–90), the Federal Republic (West Germany) recognized all types of objectors, providing noncombatant service and alternative civilian service, while after 1964 East Germany (German Democratic Republic) provided noncombatant military services for conscientious objectors.