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The International Criminal Court in The Hague, Netherlands war crimes
The International Criminal Court in The Hague, Netherlands war crimes

The International Criminal Court in The Hague, Netherlands. Image: Shutterstock

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Tipsheet for Investigative Journalists on War Crimes and What Is Legal in War

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Editor’s Note: Amid wars in Europe, Africa, and the Middle East, GIJN has created this tipsheet for journalists on understanding the laws of war and what does — and does not — constitute a war crime. It is based on the legal background chapter, by Dr. Claire Simmons, from the GIJN Reporter’s Guide to Investigating War Crimes. 

What is lawful in war is not the same as what is morally right, and reporting and investigating war and conflict are critical, whether or not a war crime may have been committed. However, an accurate understanding of the applicable laws by journalists can ensure and improve credible reporting, and raise awareness of potential violations. This in turn can put pressure on governments and those with international responsibilities to investigate and prosecute perpetrators.

investigating war crimes reporting guide

The GIJN Reporter’s Guide to Investigating War Crimes offers an in-depth, 16-chapter look at covering this difficult topic. Image: Victims of a massacre by Colonel Muammar Gaddafi’s forces in Tripoli. Image: Courtesy of Ron Haviv, VII

Under international law today, the term “war crime” refers to specific, serious violations of international humanitarian law that lead to individual criminal responsibility. Not all violations of the laws in war are war crimes, however, and not all civilian deaths in war constitute war crimes, or even violations. Furthermore, the applicable laws of war and the enforcement mechanisms available (including international courts) depend on which treaties have been signed by which state.

Although the common understanding of the term “war crime” may have become divorced from the legal context, there is still value in understanding its precise legal meaning as well as the broader laws that apply in war, to ensure accurate  reporting and possibly contribute to combating impunity for war crimes. To do so, we recommend reading the full chapter on What is Legal in War from the GIJN Reporter’s Guide to Investigating War Crimes.

Not All Laws Apply to All States

Under international law, states are only bound by the laws to which they have agreed, usually through ratification of treaties (signing and implementing them in domestic law), or through customary international law. The UN Treaty Database, the ICRC IHL Database, and other online resources contain lists and information on which states have ratified which treaties.

Parties to an armed conflict are bound by:

Treaty law, which is only binding on the states that have ratified the treaty in question.

  • International humanitarian law treaties, such as the Four Geneva Conventions of 1949, which have been ratified by every recognized state (but which lack detailed provisions regarding certain rules, including those applicable to non-international armed conflicts); and their Additional Protocols of 1977 (which have not been ratified by all states; notable among these are the US, Pakistan, and Iran).
  • International criminal law treaties, such as the Rome Statute of the International Criminal Court, which has been ratified by 123 states. Some notable states that have not ratified this statute include the US, China, Israel, Russia, Ukraine, and Yemen. (See “war crimes courts” in the full chapter below for some exceptional circumstances).
  • International human rights law treaties, such as the International Covenant on Civil and Political Rights, International Covenant on Economic, Cultural, and Social Rights, the European Convention on Human Rights, the Inter-American Convention on Human Rights, and the African Charter on Human and Peoples’ Rights.

Customary international law, which refers to laws derived from the practice of states and their acceptance as law, even though they may not be written down in treaties ratified by that state.

  • All parties to an armed conflict are bound by customary international law, including non-state armed groups.
  • For example, even though some states have not ratified Additional Protocol I of the Geneva Conventions, which includes the rule that civilians may not be targeted (Article 48), this rule is still considered customary international law binding on all parties to an armed conflict.
  • Customary law can be difficult to determine, however. The ICRC customary international law database, while not a legal source in and of itself, is a good reference to understand which rules may exist as customary international law in armed conflict.

The legality of starting an armed conflict is governed by separate rules of international law (laws on the use of force between states). But how or why a conflict started does not affect the rules that apply in armed conflict. In short, the same international humanitarian laws apply whether an armed conflict was started illegally or not.

Caption/Description: The courtroom at the International Criminal Tribunal for the former Yugoslavia, a body of the United Nations established to prosecute the war crimes committed during the Yugoslav Wars and try their perpetrators. The tribunal was an ad hoc court located in The Hague, Netherlands.

The courtroom at the International Criminal Tribunal for the former Yugoslavia, a body of the United Nations established to prosecute the war crimes committed during the Yugoslav Wars and try their perpetrators. The tribunal was an ad hoc court located in The Hague, Netherlands. Image: Courtesy of Ron Haviv, VII

Rules of War

Detailed rules exist to regulate the conduct of hostilities under international humanitarian law, as well as to afford protections to those not or no longer taking part in hostilities (e.g., those in detention, the sick, and wounded). The rules laid out below are indicative of some of the main principles and protections under international humanitarian law, but are not exhaustive.

Conduct of Hostilities

Two fundamental rules applicable to the conduct of hostilities are the principles of distinction and proportionality.

  • Distinction

The principle of distinction dictates that parties to an armed conflict must always distinguish between civilians and those taking part in hostilities (including combatants), as well as between civilian objects and infrastructure and military objectives. Only military objectives and those taking part in hostilities may be lawfully targeted for attack.

Who may be targeted? In terms of persons, only combatants and those taking a direct part in hostilities are lawful targets. However, civilians killed or harmed are not necessarily the result of an unlawful attack, if all the rules of targeting were respected.

Under international humanitarian law, the term “combatant” has a specific legal definition, meaning all members of a state’s armed forces (excluding medical and religious personnel). Combatants are considered military objectives and, thus, can be lawfully targeted, unless they are hors de combat (i.e., they are wounded, sick, or have surrendered), and are entitled to prisoner of war status if captured by the enemy.

In addition, anyone who is not a combatant is legally considered a “civilian,” under international humanitarian law. However, civilians may lose their legal protection from attack if they take a direct part in hostilities, although the details of when and for how long they lose this protection are sometimes contested. Members of organized non-state armed groups participating in hostilities may be considered to have lost their protection from attack for the duration of their membership to that armed group. Terms like “fighter” or “continuous combat function” are sometimes used to denote members of these armed groups.

Whatever their actions, both combatants and civilians can never lose all the protections afforded to them under international law, including the right to humane treatment.

What may be targeted? Military objectives include anything that effectively contributes to the military effort by their location, purpose, or use, and whose partial or total destruction would offer a definite military advantage in the circumstances at the time. Objects or infrastructure that are civilian by nature (e.g. civilian buildings, bridges, roads) may therefore become military objectives depending on the circumstances, for example if they are used to house or transport military equipment. Nevertheless, both sides to the conflict have an obligation to avoid the military use of certain civilian objects, especially medical facilities (see below on protected emblems and perfidy).

If any doubt exists about whether a person or an object is military or civilian, they are presumed to be civilian and prohibited from attack.

  • Proportionality

The principle of proportionality dictates that an attack is unlawful if it will cause civilian harm that is much greater than the direct military advantage anticipated from the attack. For example, bombing a low-value objective, such as an empty military truck, in a busy marketplace, thus killing many civilians, would probably fail the proportionality test.

On the other hand, an attack that causes injury or death to civilians or damage to civilian infrastructure may not be unlawful if the anticipated military advantage is greater than the amount of civilian harm (which is sometimes referred to as “collateral damage” or “incidental harm”). Thus, not all civilian deaths constitute war crimes or violations of international humanitarian law. The proportionality principle depends on what was known at the time of the decision-making and the attack, and is not assessed by evidence that may become clear after the fact. Furthermore, it is based on a balance between humanity and military necessity, for which there is no exact calculation. This can make it particularly difficult to assess compliance.

Precautions in Attack

Deciding whether or not an attack is lawful under international humanitarian law (i.e., whether it respects the principles of distinction and proportionality) requires those planning and carrying out military operations to take feasible precautions when attacking. This includes exercising constant care to spare civilians during military operations, verifying that the objective is military not civilian, canceling or suspending the attack if the force used will be indiscriminate or disproportionate, and providing warnings in attack when appropriate.

The obligation of precautions also applies to protecting civilians and civilian objects against the effects of attack, for example, by choosing not to station military equipment or personnel in densely populated areas or in vulnerable civilian infrastructure sites, like hospitals.


International humanitarian law further regulates the means and methods of warfare, This includes weapons that, by their nature, are indiscriminate — if they cannot distinguish between lawful and unlawful targets — and those that would cause superfluous injury or unnecessary suffering. Certain weapons are further prohibited or regulated under certain treaties (e.g. biological and chemical weapons, land mines, expanding bullets).

Other Protections Under International Humanitarian Law

International humanitarian law also provides protections for those that are not or are no longer taking part in hostilities. Some of these are summarized here.

  • Treatment of Those in Custody

Anyone not or no longer taking part in hostilities must be treated humanely in all cases, including being protected from torture or inhuman and degrading treatment. Civilians detained for reasons related to the armed conflict are entitled to specific judicial guarantees in international armed conflicts. Prisoners of war — a status that only exists in international armed conflicts — are entitled to specific protections detailed in the Third Geneva Convention of 1949, including entitlement to judicial guarantees, protection from serving in the forces of the hostile power, and rules related to their communication with the outside world.

  • Occupation

Specific rules exist under international humanitarian law governing occupation, which is always supposed to be temporary in nature. These laws include details about the governing of the territories as well as prohibitions on forcible displacements and collective punishments. Furthermore, occupying powers will most likely have international human rights law obligations with regard to those under their control.

  • Misuse of Protected Emblems

International humanitarian law provides for enhanced protection in certain cases, including for the use of the red cross, red crescent, and red crystal emblems. The protected use of these emblems is crucial for the respect of humanitarian rules in armed conflict. Parties to a conflict must trust that no one, including their adversaries, is misusing the emblems in order to maintain their significance of neutrality and protection. Misrepresenting any civilian or protected status, including these emblems, is a violation of international humanitarian law. Committing perfidy, namely using these protections in order to kill, injure, or capture, constitutes a war crime.

Red Cross emblem war crimes investigation

An International Committee of the Red Cross refugee assistance tent in Lviv, Ukraine, March 2022. Misuse or misrepresentation of the red cross, red crescent, or red crystal symbols to disguise or protect combatants or military materiel is a violation of international humanitarian law. Image: Shutterstock

War Crimes

The term “war crimes” refers to a subset of serious violations of international humanitarian law that lead to individual criminal responsibility. Violations of the principles of distinction and proportionality constitute war crimes, as do torture and inhuman treatment of those in custody, or perfidious use of protected emblems. The Rome Statute of the International Criminal Court contains a list of war crimes in international and non-international armed conflict. Despite the fact that not all states have ratified the Rome Statute, the war crimes listed within are generally considered to represent the customary international understanding of the term.

States have an obligation to investigate war crimes committed by their armed forces and nationals, as well as those committed within their territory and/or jurisdiction, and if appropriate, prosecute the suspects. They may also choose to investigate and prosecute any war crime, regardless of where and by whom it was committed, a principle known as “universal jurisdiction.”

Genocide and Crimes Against Humanity

Genocide and crimes against humanity are two other forms of international crimes, which were also concepts that emerged following the Second World War to prosecute the international crimes committed in previous years. Both are now codified within the Rome Statute of the International Criminal Court. The 1948 Genocide Convention is also considered customary international law binding on all states. Genocide and crimes against humanity have different criminal elements than war crimes.

  • Crimes against humanity must be committed as part of a “widespread or systematic attack.”
  • Genocide must be committed “with the intent to destroy, in whole or in part, a national, ethnical, racial, or religious group.”
  • Genocide and crimes against humanity can be committed in or outside of armed conflict.

Other Violations

War crimes are not the only violations of international humanitarian law which lead to serious consequences. Other violations, such as the failure to take precautions in attack, may lead to loss of life or serious injury to civilians and/or civilian property, even though one individual person may not be criminally responsible for the act. Misusing the protecting emblems can constitute a war crime if it is done perfidiously, but in all cases it also constitutes a violation of international humanitarian law and can have serious consequences if it undermines trust in medical and humanitarian objects and personnel. States have an obligation to investigate and suppress these possible violations.

Command Responsibility

The concept of command responsibility is a unique concept under international law that can lead to commanders being held directly responsible for the acts of their subordinates. Under international criminal law, this can extend to civilian superiors (not only military commanders). There are two forms of such responsibility.

  • Command responsibility for ordering their subordinates to commit war crimes.
  • Command responsibility for failing to prevent, repress, or report war crimes (e.g., failing to investigate and prosecute war criminals under their command).

This concept has been examined in detail by international criminal tribunals. There are various legal elements to the concept that must be met, including that the commander “knew or should have known” about the war crimes, and that they did not take the “necessary and reasonable” measures within their power to act.

‘Alleged’ or ‘Possible’: Determining the Existence of a War Crime or Violation

Journalists should bear in mind that their investigations will rarely be able to prove the existence of violations of international law by themselves.

When observing or reporting on an incident, it usually won’t be possible to establish the existence of a war crime. All individuals, including those accused of war crimes, have the right to a fair trial and the presumption of innocence (or an equivalent right in domestic legislation). For this reason, designating an act as a war crime or other violation of humanitarian law may only be established by a court after an effective investigation and trial has been carried out. When reporting on acts that may constitute war crimes, it is legally accurate to report on “alleged” or “possible” war crimes.

In most cases, establishing the existence of a violation of international humanitarian law will also require information that is internal to military or state institutions. For example, this could include contemporaneous accounts and knowledge about the attack, what intelligence was used, what the actual target was, how the expected civilian harm was calculated and balanced to the anticipated direct military advantage, and what feasible precautions were taken.

States have the primary obligation to conduct investigations into possible violations. When they fail to effectively investigate, other bodies may step in, including international bodies such as the International Criminal Court or UN agencies. Civil society, including journalists and human rights organizations, can have an important role to play in raising awareness about possible or alleged violations, as well as calling out states on their failure to investigate them. Understanding the law and pointing out possible violations can be a powerful call to action. In many cases, these non-state investigative efforts may lead to eventual accountability. Nevertheless, journalists should bear in mind that their investigations will rarely be able to prove the existence of violations of international law by themselves, and efforts should be made not to compromise potential future investigations.

Dr. Claire Simmons international humanitarian law University of EssexDr. Claire Simmons is a legal expert on international humanitarian law. She is a Senior Lecturer at the Royal Military Academy Sandhurst, and Fellow of the University of Essex Armed Conflict and Crisis Hub. She has experience working on international humanitarian law and human rights in academic institutions and nonprofit organizations. The views expressed in this chapter are those of the author and do not necessarily reflect the views or positions of any affiliated entities.


Ron Haviv, VII FoundationRon Haviv is an Emmy-nominated filmmaker, award-winning photojournalist, and co-founder of the photo agency VII, dedicated to documenting conflict and raising human rights issues around the globe. He is also the co-founder of the nonprofit VII Foundation, which concentrates on documentary projects and provides free visual journalism education.

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