The word civilian is derived from the Latin verb “civilis” meaning “of the people.” A citizen is someone who is not a member of an army or armed force and therefore does not take part in war. Civilians are generally not treated as combatants and are therefore protected by the laws of war and international humanitarian law. This includes the 1949 Geneva Conventions and the 1977 Additional Protocols. These treaties describe the rights and protections that are guaranteed to civilians during armed conflict, regardless of whether it is an internal (civil war) or international (war) armed conflict.
Civilian is also used to refer to the population of a country or region who are not members of the military forces fighting against an armed insurrection. The population of civilians is typically a large group, and if the country or region are not at peace, the number of civilians in the area may be very high. A country’s constitution or other legal document may define the definition of civilian and set the number of citizens in the population.
While some countries have constitutional provisions defining the population of civilians, most do not. Instead, they rely on the definition of civilians in international humanitarian law, which was originally defined in 1949 by the Fourth Geneva Convention and has been reinforced by the Additional Protocols. International humanitarian law defines civilians as persons who do not belong to definite categories of persons, such as members of the armed forces or other belligerent parties, and excludes from civilians anyone who takes direct part in hostilities (API Arts. 45.1, 51.3). Some practice adds the condition that civilians who directly participate in hostilities lose their protection from attack and become liable to be attacked as combatants under their own law, even though the notion of direct participation in hostilities is not clear from the treaty text itself.
In addition to protecting the general civilian population, humanitarian law guarantees certain privileges for civilians in particular circumstances such as those in occupied territories and during evacuations and internment (API Arts. 48-56). It also requires that the Parties to an armed conflict endeavour to conclude local agreements for the removal from besieged or encircled areas of wounded and sick civilians, ministers of all religions, and medical personnel and equipment; and that civilian hospitals organized to give care to them should be respected and protected (API Arts. 13-18).
In the context of a policy-relevant civil-military relationship, a civilian is often a person who has experience and expertise that complements and guides professional military advice. This experience and expertise can be in the form of a political or management career, which prepares a person to understand the ways that society and public institutions are organized and resourced, or it may come from an academic discipline such as social science or law. In either case, the civilian’s insights into the nature of power in a specific political context can be invaluable to the military and the broader society.