is book aims to clarify the current debates regarding the concept of proportionality
in international humanitarian law (IHL).
Almost all states involved in armed conicts recognize the principle of proportionality
in IHL as a legal and ethical restraint on their military activities.
Specically, it is broadly accepted that an attacking party cannot justify collateral
damage to civilians if the harm caused is expected to be excessive with regard
to the concrete military advantage gained. However, the precise meaning
of this principle is frequently disputed. ere are debates over many issues, including
the degree to which force- protection measures can justify extensive
collateral damage; the obligation to employ accurate but expensive weaponry;
and the impact of using voluntary and non- voluntary human shields. ere are
also disagreements concerning the parameters that are supposed to be used in
assessing such a case: What exactly is a “military advantage,” and what does it
mean for the harm caused to “exceed” such an advantage?
Controversy is especially rife regarding asymmetrical conicts. Many states,
among them many democracies, are engaged in armed conicts against non- state
actors, some of them terrorist organizations. In these situations, questions relating
to the correct interpretation and eective implementation of the principle of proportionality
have arisen, for example, in connection with targeted killings and
military operations in civilian areas.