These are the three basic principles of IHL:

1- Distinction: The principle of distinction requires those who wage war to distinguish between people who take part in the hostilities and those who do not (or no longer) take part in them. This is what IHL calls “the principle of distinction”.
The principle of distinction, along with the principle of protecting the civilian population, is fundamental to IHL.

According to this principle, warring parties must distinguish at all times between civilians and combatants, and between civilian objects and military objectives. As a result, they are obliged to direct military operations only against military objectives.

In case of doubt, a person must be considered a civilian and therefore not be targeted. The same applies to objects normally used for civilian purposes.

In short:
– Attacks on civilians are prohibited.
– Attacks on civilian objects (houses, hospitals, schools, places of worship, cultural or historical monuments, etc.) are prohibited.
– The use of weapons that do not distinguish between civilians or civilian objects and military targets is prohibited.

2- Proportionality: Means corresponding in size or amount to something else.

In domestic law, the principle of proportionality often refers to the idea that the punishment of a certain crime should be in proportion to the severity of the crime itself.

The principle of proportionality states that even if there is a clear military target, it may be attacked only if the risk of civilians or civilian property being harmed, or of civilians being killed, is not excessive in relation to the expected military advantage.

The number of dead and wounded among the civilian population and the damage to civilian objects must not be excessive in relation to the expected military advantage.

3- Precaution: The premise underlying the principle of precaution is that constant care must be taken by all those involved in the planning and execution of attacks to spare the civilian population and civilian objects. In other words, this principle holds that precautions must be taken in order to comply with the principles of distinction and proportionality.

The principle of precaution requires that civilians be given advance warning (by loudspeaker, over the radio, using easily understood signals, by dropping leaflets, etc.) when planned attacks on military objectives may harm them, unless the tactical situation does not permit it.

The principle of precaution also applies to the choice of weapons and tactics. If a commander wants to destroy a military building next to a football field, doing it at night when there are no civilians playing football would most likely be a sound precaution.