IEEE Technology and Society Magazine - March 2018 - 58

Theoretical Foundations for the Discussion
The arguments I will present against AWSs rely on these
weapons not being currently capable of complying with
IHL. However, my interest in IHL is not qua law, but due
to its narrow relation to just war theory - a normative
framework often used by ethicists to discern the permissibility and the justification of the use of force.

Just War Theory
Just War Theory regulates both the reasons for going to
war ( jus ad bellum), and the conduct of war ( jus in
bello). I introduce only the latter because the former is
less relevant to the discussion.
According to the traditionalist view of Just War Theory, there are three core principles of that regulate
conduct in war: discrimination, proportionality, and
military necessity. These principles aim to limit violence and minimize harm towards non-combatants; and
where harm does occur, even if it is foreseeable, it must
be a collateral effect, i.e., unintended.3 Widdows [15]
describes these three key principles as follows:
1) Discrimination. To be just, combatants must distinguish between enemy combatants and noncombatants.
2) Proportionality. To be just, the harms of any action
must be proportional to the gains.
3) Military Necessity. To be just, any action must be
militarily necessary to achieve the end with the minimum harm.

International Humanitarian Law
International Humanitarian Law can be seen as an operationalization in treaties and conventions of the abstract
principles comprised in jus in bello, which are specially
addressed in the four Geneva Conventions of 1949 and
the so-called additional protocols of 1977.
The ICRC [16] defines international humanitarian
law as:
a set of rules which seek, for humanitarian reasons, to limit the effects of armed conflict. It protects persons who are not or are no longer
participating in the hostilities and restricts the
means and methods of warfare.
The aim of IHL is to protect and minimize the harm
inflicted to unlawful targets (those who are not taking
part in hostilities), and make sure military force is only
used against legitimate targets. The principles of distinction, proportionality, and precaution are codified in IHL
allowing for the killing of some people (combatants)
3
This is based on the doctrine of double effect. This doctrine accounts for
the permissibility of an action that causes a serious harm as an unintended
effect of achieving some good end.

under specific circumstances, but prohibiting the killing
of others (innocent civilians or wounded soldiers), and
specifying lawful objects (e.g., a military factory) and
unlawful objects (e.g., a school).
IHL also stipulates restrictions on the means and
methods of warfare: "[a]s a general rule, IHL prohibits
means and methods of warfare that cause superfluous
injury or unnecessary suffering" [16].
IHL offers, thus, general rules and principles to govern the conduct of hostilities, irrespective of the weapon
used. Nonetheless, specific treaties have banned or
restricted the use of many weapons, such as chemical
and biological weapons, blinding lasers, or anti-personnel mines. These weapons are considered illegal per se,
i.e., weapons that violate IHL irrespective of their use
because they can't comply with its key principles. Even
though a biological weapon could be used, in theory, to
target a legitimate military target, in practice, the infected target could spread the biological agent - i.e. the
disease - to innocent civilians in an unpredictable way,
which would violate the principles of IHL. Weapons that
are illegal per se are different from weapons that are
used in an illegal manner, an AK-47 assault rifle is not
illegal per se because it could be used in a way that
complies with IHL. However, it would be of course illegal
to use it to coerce civilians or to execute surrendering
enemy combatants.

Killer Robots' Failure to Discriminate:
Arguments and Counterarguments
In this section I present a series of arguments in favor of
a ban based on AWSs' failure to comply with the principle of discrimination, which is a necessary condition for
permissible war. After presenting arguments in favor of
a ban, I will discuss a series of counterarguments
offered by opposers of the ban.
A key argument against AWSs is that autonomous
systems can't properly discriminate between combatants and non-combatants in a way that satisfies the
requirements of IHL. Sharkey [1], himself a robotics
expert, argues that robots do not currently have the
capacity to make this distinction. His objections are: 1)
Computers do not have adequate sensory processing
systems for separating combatants from civilians, they
do have cameras and other sensors, and might thus be
able to tell whether something is human or not, but
not more than that. 2) A computer needs that every
element is specified in sufficient detail in a software
program, so it can operate on it, but there is no adequate definition of a civilian that can be translated into
computer code. 3) Even if computers had adequate
visual sensing mechanisms to distinguish civilians
from combatants, machines will still lack the contextual awareness necessary for discrimination decisions.

IEEE Technology and Society Magazine

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MARCH 2018

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