HUMANITARIAN AND SECURITY LAW
LECTURE NOTES: JUS IN BELLO
4. JUS IN BELLO
4.1.INTRODUCTION
► Two topics will be discussed in this lecture – the core of humanitarian law (jus in bello) and the EU involvement
in Security Law (hence the name of the course).
4.2. JUS IN BELLO – FUNDAMENTAL PRINCIPLES AND RELATION TO OTHER AREAS OF
INTERNATIONAL LAW
PUBLIC INTERNATIONAL LAW
► IHL is a sub-branch of Public International Law
o General doctrines and principles of international law apply.
o Sources: treaties / customary international law / general principles
▪ Cf. 2005 Study ICRC “Customary Humanitarian Law”
• Has significant impact on states (politically), because if they had never ratified the
Protocols of the Geneva Conventions → still bound by customary humanitarian law →
this had led to some backlash.
o Jurisdiction (e.g., universal jurisdiction)
▪ 1949 Geneva Conventions established universal jurisdiction to grave breaches (war crimes).
o State Responsibility
▪ State-armed groupings will trigger state responsibility → Questions when are acts attributable
to States and what are possible excuses (ILC, 2001 Articles on State Responsibility for
Internationally Wrongful Acts).
CUSTOMARY INTERNATIONAL LAW AS SOURCE OF IHL
► Treaties can sometimes be difficult to apply or agree upon, they need consent to apply everywhere→ The need
to fill in the gap of them not being party to a treaty→
► Art. 38 (1)(b) ICJ Statute: “international custom, as evidence of a general practice accepted as law”.
► ILC: ‘“Customary international law” means those rules of international law that derive from and reflect a general
practice accepted as law’
► Two constituent elements (‘two-element’ approach):
o i) objective/material element, i.e., State practice (consuetudo/usus) => = the ‘raw material’ of CIL:
‘material and detectable acts’
▪ Uniform and steady (cf. ICJ, Asylum, 1951)
▪ Not necessarily perfect (cf. ICJ, Nicaragua, 1986)
▪ Short period of time may suffice (“instant custom”) → has to do with intensity and frequency
of state behaviour.
o ii) subjective/psychological element, i.e. conviction that rule is binding legal rule (opinio juris)
▪ “A sense of legal obligation”. Difference with practice based on considerations of ‘courtesy,
good-neighbourliness and political expediency’, convenience, tradition, habit, usage, reciprocal
tolerance or comity (comitas gentium)
1
, HUMANITARIAN AND SECURITY LAW
LECTURE NOTES: JUS IN BELLO
1. State practice
o Uniform and steady (cf. ICJ, Asylum 1951→ Peru and Colombia about the existence of a rule of
customary law at the regional level about Where there is a right to diplomatic asylum)→ no because
practice of diplomatic asylum is too diverse, it’s not sufficiently uniform and stead to talk about this
element of state practice
o Not necessary perfect (cf ICJ, Nicaragua, 1986)→ brought the case against the US → yes you may have
a treaty provision that is applicable , but at the same time there is a right to self defence
o Short period of time may suffice (instant custom)
2. Opinio juris
o A sense of legal obligation. Difference with practice based on considerations of courtesy, good-
neighbourliness and political expendiecy, convenience, tradition, habit, usage, reciprocal tolerance or
comity.
► Complex; not exact science; inductive process
o You need to look at empirical facts.
► Importance of documentation (cf. ICRC study / ICJ)
► ICRC Study on Customary IHL
o Attempt to establish the rules on customary law
o 161 Rules (very precise)
o Can be found online.
o Widely accepted in e.g., ICTY case-law
o Advantages of Customary IHL:
▪ Is also binding for those States that have did not ratify the relevant treaties.
▪ Fills the lacunae of codified rules (especially for NIAC – non-international armed conflicts which
are predominant today).
o Contested for NIACs (because of the principles of non-interference in domestic affairs)
o The methodological problématique of establishing customary IHL: criticism U.S. and reply J.M.
Henckaerts (ICRC)
▪ The US State Department (during Bush, who had invaded Iraq without UNSC authorization)
criticized the ICRC Study. During this time the US Presidential administration was very critical
and opinionated regarding IHL and Public International Law in general.
• Some even claimed IHL had become obsolete (Defence Minister)– US during that time
created the idea of the Guantanamo Bay detention camps. => damaging to the US
reputation.
▪ Legal Counsel of the US State Department (John B. III) criticised the ICRC Study.
▪ ICRC Response: “A study on customary international law has to look at the combined effect of
what states say and what they actually do. As a result, ‘‘operational State practice in connection
with actual military operations’’ was collected and analysed. To the extent that they were
available, the Study considered official reports and statements on the conduct of actual military
operations … But an examination of operational practice alone is not enough. In order to arrive
at an accurate assessment of customary international law one has to look beyond a mere
description of actual military operations and examine the legal assessment of such operations.
This requires an analysis of official positions taken by the parties involved, as well as other
states. When a given operational practice is generally accepted – for example military
installations are targeted – this supports the proposition underlying that practice, namely that
military installations constitute lawful military targets. But when an operational practice is
generally considered to be a violation of existing rules – for example civilian installations are
targeted – that is all it is, a violation. Such violations are not of a nature to modify existing rules;
they cannot dictate the law. … This explains why acts such as attacks against civilians, pillage
and sexual violence remain prohibited notwithstanding numerous reports of their commission.
2
LECTURE NOTES: JUS IN BELLO
4. JUS IN BELLO
4.1.INTRODUCTION
► Two topics will be discussed in this lecture – the core of humanitarian law (jus in bello) and the EU involvement
in Security Law (hence the name of the course).
4.2. JUS IN BELLO – FUNDAMENTAL PRINCIPLES AND RELATION TO OTHER AREAS OF
INTERNATIONAL LAW
PUBLIC INTERNATIONAL LAW
► IHL is a sub-branch of Public International Law
o General doctrines and principles of international law apply.
o Sources: treaties / customary international law / general principles
▪ Cf. 2005 Study ICRC “Customary Humanitarian Law”
• Has significant impact on states (politically), because if they had never ratified the
Protocols of the Geneva Conventions → still bound by customary humanitarian law →
this had led to some backlash.
o Jurisdiction (e.g., universal jurisdiction)
▪ 1949 Geneva Conventions established universal jurisdiction to grave breaches (war crimes).
o State Responsibility
▪ State-armed groupings will trigger state responsibility → Questions when are acts attributable
to States and what are possible excuses (ILC, 2001 Articles on State Responsibility for
Internationally Wrongful Acts).
CUSTOMARY INTERNATIONAL LAW AS SOURCE OF IHL
► Treaties can sometimes be difficult to apply or agree upon, they need consent to apply everywhere→ The need
to fill in the gap of them not being party to a treaty→
► Art. 38 (1)(b) ICJ Statute: “international custom, as evidence of a general practice accepted as law”.
► ILC: ‘“Customary international law” means those rules of international law that derive from and reflect a general
practice accepted as law’
► Two constituent elements (‘two-element’ approach):
o i) objective/material element, i.e., State practice (consuetudo/usus) => = the ‘raw material’ of CIL:
‘material and detectable acts’
▪ Uniform and steady (cf. ICJ, Asylum, 1951)
▪ Not necessarily perfect (cf. ICJ, Nicaragua, 1986)
▪ Short period of time may suffice (“instant custom”) → has to do with intensity and frequency
of state behaviour.
o ii) subjective/psychological element, i.e. conviction that rule is binding legal rule (opinio juris)
▪ “A sense of legal obligation”. Difference with practice based on considerations of ‘courtesy,
good-neighbourliness and political expediency’, convenience, tradition, habit, usage, reciprocal
tolerance or comity (comitas gentium)
1
, HUMANITARIAN AND SECURITY LAW
LECTURE NOTES: JUS IN BELLO
1. State practice
o Uniform and steady (cf. ICJ, Asylum 1951→ Peru and Colombia about the existence of a rule of
customary law at the regional level about Where there is a right to diplomatic asylum)→ no because
practice of diplomatic asylum is too diverse, it’s not sufficiently uniform and stead to talk about this
element of state practice
o Not necessary perfect (cf ICJ, Nicaragua, 1986)→ brought the case against the US → yes you may have
a treaty provision that is applicable , but at the same time there is a right to self defence
o Short period of time may suffice (instant custom)
2. Opinio juris
o A sense of legal obligation. Difference with practice based on considerations of courtesy, good-
neighbourliness and political expendiecy, convenience, tradition, habit, usage, reciprocal tolerance or
comity.
► Complex; not exact science; inductive process
o You need to look at empirical facts.
► Importance of documentation (cf. ICRC study / ICJ)
► ICRC Study on Customary IHL
o Attempt to establish the rules on customary law
o 161 Rules (very precise)
o Can be found online.
o Widely accepted in e.g., ICTY case-law
o Advantages of Customary IHL:
▪ Is also binding for those States that have did not ratify the relevant treaties.
▪ Fills the lacunae of codified rules (especially for NIAC – non-international armed conflicts which
are predominant today).
o Contested for NIACs (because of the principles of non-interference in domestic affairs)
o The methodological problématique of establishing customary IHL: criticism U.S. and reply J.M.
Henckaerts (ICRC)
▪ The US State Department (during Bush, who had invaded Iraq without UNSC authorization)
criticized the ICRC Study. During this time the US Presidential administration was very critical
and opinionated regarding IHL and Public International Law in general.
• Some even claimed IHL had become obsolete (Defence Minister)– US during that time
created the idea of the Guantanamo Bay detention camps. => damaging to the US
reputation.
▪ Legal Counsel of the US State Department (John B. III) criticised the ICRC Study.
▪ ICRC Response: “A study on customary international law has to look at the combined effect of
what states say and what they actually do. As a result, ‘‘operational State practice in connection
with actual military operations’’ was collected and analysed. To the extent that they were
available, the Study considered official reports and statements on the conduct of actual military
operations … But an examination of operational practice alone is not enough. In order to arrive
at an accurate assessment of customary international law one has to look beyond a mere
description of actual military operations and examine the legal assessment of such operations.
This requires an analysis of official positions taken by the parties involved, as well as other
states. When a given operational practice is generally accepted – for example military
installations are targeted – this supports the proposition underlying that practice, namely that
military installations constitute lawful military targets. But when an operational practice is
generally considered to be a violation of existing rules – for example civilian installations are
targeted – that is all it is, a violation. Such violations are not of a nature to modify existing rules;
they cannot dictate the law. … This explains why acts such as attacks against civilians, pillage
and sexual violence remain prohibited notwithstanding numerous reports of their commission.
2
