The Balancing Act: Understanding Proportionality in Armed Conflict

In the chaos of armed conflict, where military commanders face life-and-death decisions in split seconds, international law imposes a crucial restraint: the principle of proportionality. This fundamental rule of International Humanitarian Law requires that even when attacking legitimate military targets, the expected civilian harm must not be excessive compared to the anticipated military advantage. While simple in concept, proportionality represents one of the most complex and contested aspects of modern warfare.

What proportionality means in armed conflict 🔗

Proportionality prohibits attacks that are expected to cause incidental civilian casualties or damage that would be excessive relative to the concrete and direct military advantage anticipated. This rule, codified in Additional Protocol I to the Geneva Conventions and recognized as customary international law, applies to all parties in both international and non-international armed conflicts.

Unlike the absolute prohibition on directly targeting civilians, proportionality acknowledges that civilian casualties may occur during legitimate military operations. However, it establishes a legal boundary: when the expected civilian harm would be excessive compared to the military advantage, the attack becomes unlawful.

The principle operates alongside other fundamental IHL rules. The principle of distinction requires parties to differentiate between civilians and combatants, between civilian objects and military objectives. Military necessity permits only force required to achieve legitimate military objectives. The duty of precaution mandates feasible measures to minimize civilian harm. Together, these principles create the framework governing the conduct of hostilities.

The challenge of comparing incomparable values 🔗

IHL provides no objective standard for assessing what constitutes excessive civilian harm in relation to a given military advantage. This inherent ambiguity creates a zone of discretion for military commanders while making legal accountability more difficult to establish.

The most fundamental challenge is that proportionality demands comparing essentially incommensurable values: military advantage versus human lives and civilian infrastructure. How many civilian casualties are proportionate to the elimination of a high-value military target? This moral and legal question defies simple quantification.

Military commanders must assess proportionality based on information available at the time of the attack, not with the benefit of hindsight. They often must make these calculations with imperfect information about the precise number of civilians present in a target area, the exact function of dual-use facilities serving both civilian and military purposes, and the potential for unintended consequences.

Defining military advantage 🔗

The expected military advantage must be concrete and immediate, meaning substantial and relatively near-term rather than long-term or speculative. Military advantages that are barely perceptible or would only appear in the distant future should be disregarded in the proportionality assessment.

The proportionality rule must be assessed in relation to the tactical military advantage gained in securing each specific objective of an attack, not broad strategic goals. A global strategic objective, such as winning the war, cannot be used to justify any level of civilian harm, as this would always outweigh civilian protection and nullify the proportionality requirement.

Unpacking the legal concepts of excessive harm, concrete and direct military advantage, and anticipated consequences so they can be effectively applied in combat operations raises complex interpretative challenges for military commanders and legal advisers.

The reasonable military commander standard 🔗

International law applies a reasonable military commander standard when evaluating proportionality decisions. This means assessing whether a reasonable commander, with the information available at the time, could have concluded that the expected civilian harm was not excessive relative to the anticipated military advantage.

The International Criminal Tribunal for the Former Yugoslavia acknowledged that proportionality assessments involve a relatively subjective determination, but emphasized that this does not excuse commanders from making good-faith assessments based on available information and taking all feasible precautions.

Military commanders bear responsibility for conducting diligent pre-attack assessments to ascertain potential effects on civilians and civilian infrastructure. They must prioritize rapid acquisition and assessment of target information, constantly updating their understanding as circumstances change. This includes the duty to cancel or suspend attacks if they appear likely to be disproportionate.

Precision warfare and evolving standards 🔗

Technological advancements in precision-guided munitions, intelligence gathering, and target identification have significantly influenced how the principle of proportionality is understood and applied. As military technology becomes more sophisticated, legal and public expectations regarding the precision of attacks have increased.

The availability of precision-guided munitions may make attacks that would cause substantial civilian casualties legally disproportionate when they might have been considered proportionate in earlier eras. IHL requires parties to take all feasible precautions to minimize civilian harm, and the definition of what is feasible depends partly on available technology.

States with greater technological resources may have broader obligations to employ precision capabilities to ensure proportionality, while those with more limited means may have narrower obligations. However, all parties remain bound by the same fundamental prohibition on disproportionate attacks.

Remote warfare technologies like armed drones present new challenges. While proponents argue that drones can enhance precision and reduce civilian harm, their use has also resulted in significant civilian casualties, raising concerns about compliance with proportionality requirements. Poor image quality can compromise assessments of whether an attack is expected to cause civilian harm, let alone whether such harm may be excessive.

Proportionality in urban warfare 🔗

Modern conflicts increasingly occur in densely populated urban areas, creating particularly acute proportionality challenges. Operations in cities demonstrate how difficult it is to conduct military operations against opponents embedded in civilian infrastructure without causing significant civilian harm.

In urban environments, the distinction between military targets and civilians becomes complex, and the potential for civilian collateral damage is high. Proportionality plays a key role in the legality of attacks on targets that have dual civilian and military uses. Warning civilians to leave areas of military operations does not satisfy the proportionality requirement, as advance warning is a separate and additional precautionary measure.

Long-term and reverberating effects 🔗

The time frame for assessing both civilian harm and military advantage remains contested. Should commanders consider only immediate effects or also long-term consequences? Destruction of power plants may cause limited immediate casualties but lead to significant civilian suffering over time due to lack of electricity for hospitals, water treatment facilities, and other essential services.

Attacks on infrastructure that would be expected to cause civilian casualties soon after the attack due to loss of power at hospitals or similar consequences must be included in proportionality analysis. The key distinction is between foreseeable effects and those that are too remote or dependent on intervening conditions.

War crimes and accountability 🔗

Intentionally launching an attack knowing it will cause civilian casualties clearly excessive in relation to the concrete and direct military advantage anticipated constitutes a war crime under the Rome Statute of the International Criminal Court. This prohibition applies in both international and non-international armed conflicts.

Respect for the principles of distinction, precaution and proportionality is a core duty of military commanders when conducting hostilities and ordering attacks. Violations may trigger individual criminal responsibility for war crimes.

The challenge for prosecutors and judges is determining whether the principle was violated based on what commanders knew or should have known at the time of the attack. Criminal courts must assess whether commanders made honest evaluations based on facts and circumstances available at the time of planning, rather than judging with the benefit of hindsight.

Ongoing debates and tensions 🔗

Several tensions persist in the interpretation and application of proportionality. Some argue the standard requires a significant imbalance before an attack becomes unlawful, while others contend it should be interpreted more restrictively to enhance civilian protection.

The interpretation of military advantage remains contentious. The Rome Statute’s reference to overall military advantage differs from the ICRC’s emphasis on tactical advantage from securing each specific objective, creating potential discord between IHL and international criminal law standards.

Proportionality exists both as a general principle and as a specific rule in IHL. As a principle, it has broad scope and can take various forms throughout the Geneva Conventions and Additional Protocols. As a rule, it applies specifically to protecting civilians in the conduct of hostilities and operates on an all-or-nothing basis.

The military tendency to limit the scope of proportionality as a constraint on operations contrasts with humanitarian imperatives to strengthen civilian protection. This ongoing tension reflects the broader challenge at the heart of IHL: acknowledging the reality of armed conflict while attempting to limit its most harmful effects.

What do you think? As precision weapons technology continues to advance, should we expect proportionality standards to become more stringent? How can international law better balance the inherent subjectivity in proportionality assessments with the need for clear standards and accountability?

References

1. https://ihl-databases.icrc.org/en/customary-ihl/v1/rule14
2. https://guide-humanitarian-law.org/content/article/3/proportionality/
3. https://pilac.law.harvard.edu/commanding-knowledge-the-line-of-fire-in-the-ihl-principle-of-proportionality/
4. https://lieber.westpoint.edu/proportionality-international-humanitarian-law-principle-rule/
5. https://www.icrc.org/en/article/faq-international-humanitarian-law-drones-armed-conflict
6. https://www.justsecurity.org/91319/the-principle-of-proportionality-in-the-dod-law-of-war-manual/
7. https://casebook.icrc.org/highlight/targeting-under-international-humanitarian-law/