Introduction to IHL Series: Rules of Detention

April 27, 2026 by icji

Introduction to IHL Series: Rules of Detention

During the course of Russia’s full-scale invasion of Ukraine, there have been credible reports that Ukrainian Prisoners of War (POWs) have been executed, tortured, denied medical treatment and subject to other forms of ill-treatment, such as sexual violence. All of these crimes are explicitly prohibited by the Third Geneva Convention. A report by the Organization of Security and Cooperation in Europe (OSCE) found that these violations were systemic and widespread, and may amount to war crimes and crimes against humanity.

This post provides an overview of what international law says about the treatment of POWs, and the treatment of civilian detainees as well.

The First Geneva Convention on POWs was signed in 1929.[1] It called for the “humane” treatment of prisoners and their protection “particularly against acts of violence, from insults and from public curiosity.” It included provisions related to interrogation, safety, hygiene, conditions of confinement and personal possessions. Following World War II, the Convention was updated in 1949 by the Third Geneva Convention, to which every country in the world is a party. Additional standards are set out in Additional Protocol I, adopted in 1977, which has been ratified by more than 170 countries, including Ukraine and Russia.

POW status confers on combatants in international armed conflict, like the conflict in Ukraine. Prisoners of war are essentially detained for one purpose: to remove them from the battlefield during conflict. They cannot be prosecuted simply for participating in combat, provided that they follow the laws of war.

Those who detain prisoners of war may be prosecuted if they mistreat the prisoners. Several types of mistreatment are recognized international crimes. For example, it would be a war crime to commit any of the following offenses against a POW:

Murder;
Torture, meaning intentionally inflicting severe pain or suffering;
Inhuman treatment entailing serious pain or suffering;
Denial of a fair trial;
Forcible service or military work in a hostile army; or
Sexual violence.

Beyond the criminal law applicable to detention, the fundamental premise of how POWs must be treated remains the “humane” standard contained in the 1929 Convention. To ensure humane treatment, there are defined standards for detention covering topics such as accommodation, food, hygiene and clothing. Examples of such provisions include:

Being treated with “respect for their person and their honor.”
They cannot be subjected to coercive interrogation.
Places of confinement must be located at a safe distance from active combat and must be similar to those of the detaining authority.
POWs must be grouped according to their nationality, language and customs.
They have the right to correspond through letters and messages and receive packages with food, clothing or medical supplies.
The right to inform family and the ICRC’s Central Tracing Agency of their whereabouts through “capture cards.”
The right to adequate medical attention, including the repatriation of seriously wounded or ill POWs.
The Third Geneva Convention requires the ICRC to be given access to places of detention and the ability to interview POWs.

Deviation from these standards may be a war crime if the deviation constitutes inhuman treatment or another of the crimes listed previously. Even absent criminality, deviation from these standards may be a violation of International Humanitarian Law (IHL) for which a state can be held responsible.

Following the cessation of hostilities, POWs must be released and repatriated. There are only very limited exceptions to this rule.

The treatment of civilian detainees is governed by the Fourth Geneva Convention and is generally similar to provisions governing the treatment of POWs. Because they are not combatants, the conditions in which civilians may be detained are narrow. Detention can only be justified for imperative security reasons. In such a situation, the detained civilian must be released as soon as conditions no longer warrant continued detention. Importantly, civilian internment may not be used as punishment. A soldier who detains civilians, despite knowing there are no imperative security reasons to do so, may be found to have committed a war crime. A soldier who subjects detained civilians to torture, acts of sexual violence, or other types of inhuman treatment may also have committed a war crime, whether the victims’ initial detention was lawful or not.

In Russia’s case, it is obligated under international law to not only immediately remedy violations committed by military forces and any entity under its control, but also to prevent such violations from occurring in the future. Knowingly failing to take reasonable remedial or preventative action could result in charges against members of the Russian leadership with authority over detention facilities or their personnel under a legal concept known as “command responsibility.”

Avenues for prosecution include domestic prosecutions in Ukraine, which ICJI is supporting with legal expertise, prosecutions pursued in other countries under a legal concept of “universal jurisdiction” for grave breaches of international law, and prosecution by the International Criminal Court.

For Further Information:

[1] ICRC