20 INTERNATIONAL LEGAL PROTECTION OF HUMAN RIGHTS IN ARMED CONFLICT separated from their parents, and facilitate the re-establishment of family links and the reunification of families.19   3. The principle of distinction in international humanitarian law Possibly the most important difference between international humanitarian law and international human rights law is that the substantive protection a person benefits from under the former depends on the category that person belongs to, while under the latter all human beings benefit from all human rights, although some human rights instruments establish and protect specific rights for specific categories of persons, e.g., children, persons with disabilities or migrants. In international humanitarian law, the protection of civilians is not the same as the protection of combatants. This difference is particularly relevant in the conduct of hostilities: there is a fundamental distinction between civilians and combatants, and between military objectives and civilian objects. Combatants may be attacked until they surrender or are otherwise hors de combat, while civilians may not be targeted, unless and for such time as they directly participate in hostilities, and they are protected by the principles of proportionality and precaution against the incidental effects of attacks against military objectives and combatants. The difference also has an impact on the protection of persons who are in the power of the enemy. The protection of captured combatants who turn into prisoners of war is not the same under Geneva Convention III as that of protected civilians under Geneva Convention IV. In particular, the former may be interned without any individual procedure, while protected civilians may be deprived of their liberty only in the framework of criminal proceedings or upon individual decision for imperative security reasons. Among civilians in the power of a party to an international armed conflict, international humanitarian law in addition distinguishes between protected civilians (i.e., basically those of enemy nationality) and other civilians, who benefit only from more limited fundamental guarantees.   Protocol I, arts. 52.2 and 52.3, and Geneva Convention IV, art. 50. 19