Principles and Foundations of International Law
Universiteit van Amsterdam, Prof. dr. K.J. Keller
G. Hernández, International Law, Oxford University Press 2019
Part I – The Structure of International Law
Chapter 1 – The History and Nature of International Law
The 1648 Peace of Westphalia is (often) considered the starting-point for modern
international law in Europe. It represented a definitive rejection of the secular power of the
Pope over the internal affairs of other States. Catholic and Protestant states would henceforth
be sovereign and equal, under no higher power. Under the Peace of Westphalia, States were
free to choose which religion to adopt. They were considered equal and sovereign in their
relations with one another, without external interference unless consent was expressly given,
usually by treaty. While the concepts of sovereignty and non-interference were not new at the
time, the characterization of the State as an organized territorial entity capable of guaranteeing
its commitments were first established in Westphalia. This stands out as one of the first
modern instances of conscious, multilateral ordering through law.
The Congress of Vienna in 1815, marked the end of the Napoleonic Wars and marked a
turning point in European international relations for a number of reasons:
Certain ‘Great Powers’ within the ‘Concert of Europe’ could intervene where
necessary to preserve peace;
The Congress system was to entrench the idea that certain values needed safeguarding
through international law, which resulted in the creation of a public law system in
Europe.
Positivists contended that only laws which had been consented to by States were valid, as
these were the only entities empowered to create international law. These rules could be
consented through expressly, namely through written treaties, or they could emerge from
unwritten practice, taking the form of custom. Within domestic legal orders, law became
dependent on the will of the sovereign, and it followed that the sovereign state became central
to international law. This resulted in canonical principles, that are still vital today, including:
Sovereign equality and the requirement of consent of a State to be bound by an
obligation;
Freedom of a State from interference by another State in its internal affairs; and
The entitlement of a State to ensure its survival or self-preservation, including by acts
that might breach international law.
The 1884 Berlin Conference served to lay the legal foundation for the colonization of Africa.
The Berlin Act of 26 February 1885 purported to prohibit slavery and protect freedom of trade
and navigation. It also provided a legal basis for the acquisition of territory that European
States considered not to attain civilization and whose inhabitants could not hold sovereignty.
The lands were considered ownerless (terra nullius) so as to facilitate to conquest and
occupation of new colonies, even with substantial indigenous populations.
The most important development that marked the end of World War I was the signing of the
Covenant of the League of Nations in 1920, whose aim it was to organize the international life
of the family of nations. The League was the first organization that aspired to universal
membership, open to any fully self-governing State, Dominion or Colony; it employed the
first permanent international civil servants, working independently of all states. The League
,era was marked by the establishment of the Permanent Court of International Justice (PCJI) in
1922 in The Hague. It was the first permanent international court tasked with the mandate of
applying international law.
Another important milestone of the inter-war (1919-39) period would be the signing of the
1928 Kellogg-Briand Pact on the banning of war. In the Pact, parties forswore resort to war as
a means of national policy. It would play a crucial role in laying down a prohibition on
aggressive war which would later become embodied in the UN Charter.
After World War II, the Charter of the United Nations was signed on June 26th 1945 and came
into forced on October 24th 1945. The goal of the Charter was mainly to prevent further war
and strengthen international order, but also to promote respect for the equal rights of and self-
determination of peoples, a universal peace between States and cooperation on economic,
social, cultural, or humanitarian questions and the respect for human rights without
discrimination. It is founded on three pillars:
Peace and security – through the prohibition of recourse to war and the use of force
(art. 2(4)) and the establishment of the Security Council;
International cooperation;
Development – mostly in relation to the gaining of independence of dozens of former
European colonies in Africa and Asia. They challenged the Eurocentric orientation of
international law and sought to use international law to address their relative
disadvantage in economic, social, and political development.
Foundational concepts that underpin the current international legal order
The main purpose of international law is the regulation of relations between States and the
recognition of the doctrine that States are autonomous entities capable of expressing a will or
an interest, characterized by a number of features including an effective governmental
apparatus, and control over a distinct territory and authority over a population. International
law also regulates the conduct of international and regional organizations, which are
considered to be legal persons that have been created by States to fulfil specific functions.
International law furthermore regulates subsidiary subjects, such as individuals, multinational
corporations and non-governmental organizations.
Sovereign equality is an important pillar of international law and embraces two distinct
notions:
Equality – a formal notion. Whatever the population, economic weight, or military
power of a State, they enjoy equal footing as international legal subjects.
Sovereignty – with external and internal dimensions. Externally, the sovereign state
requires that no other state seeks to undermine the sovereignty of another state.
Internally, sovereignty endows a state with the exclusive power to exercise public
functions over individuals and territory under its jurisdiction.
A second characteristic feature is the decentralized nature of international law. International
law recognizes multiple and equal sovereign entities, States, and purports to regulate relations
between them. There is a horizontal legal order with no superior authority.
The basis of obligation of international law can be found in the consent of States and the
principle of reciprocity; the notion the States consent to limit their freedom of action in order
to induce other States to also limit their own. Consent and reciprocity are accompanied by the
requirement that obligations assumed by States be performed in good faith.
,Hart (1907-1992)
A legal system encompasses three separate categories of legal rules.
1. Primary rules, which set out standards of conduct and interaction;
2. Secondary rules, which underpinned the primary rules and confirmed their validity;
3. A master ‘rule of recognition’ which enables an observer to identify the components of the
system and to treat them as legal.
Hart’s theory depended on the ‘internal point of view’ of legal officials, systemic agents who
are entrusted with the application of secondary rules, and their acceptance of the system that
could generate primary rules through the process of secondary rules. Hart regarded
international law as lacking the ‘rule of recognition’, and also deficient with respect to
secondary rules of adjudication, enforcement and change.
Hernández believes it is too simplistic to adhere to the view that international law is not law
because it is institutionally deficient. International law contains many of the seeds of a
recognizable legal system, including recognized legal sources, international legal persons in
the form of States and international organizations, rules of interpretation to be applied by
impartial third parties, precepts of responsibility for breach, and even preemptory norms.
Criticism on international law
The development of international law has been decidedly Eurocentric, given the imperial
history of that continent and in the reality that international law was construed originally as an
extension of the European State-system. Concerns have been expressed about the purported
universality of international law, partially in relation to the negative consequences of
international law for those who have been excluded from participation in its development.
International law has been described in various ways, drawing from various schools:
Realism – dismisses law as secondary and focuses on the struggle for power between
States.
Institutionalism – suggests that though law and institutions are often instrumentalized,
they offer distinct advantages which induce States to respect law and join institutions
they regard as legitimate;
Network theories – of transnational communication, rooted in liberalism, which seek
to describe how individuals, acting within and between international institutions, are
the primary actors in international society;
Constructivism – regards all reasons for action as socially constructed, and states that
international law exists primarily as a vocabulary to justify behavior because it can
potentially constrain certain behavior, but equally facilitate other forms of behavior.
, Chapter 2 – Sources of International Law
The sources of international law can be distinguished between formal sources and material
sources:
Formal sources – the methods for law-creating that are legally binding on their
addressees and of general application. they are generally regarded as binding due to
the consent of the addressee to them.
Material sources – sources that are not legally binding but may provide evidence that
sheds light on the existence of a legally binding rule.
Article 38 of the ICJ Statute provides a list of sources of international law. Technically it lays
out only the categories of sources to be applied by the ICJ: its lex arbitri (applicable law).
Formally speaking, there is no hierarchy between the sources enumerated in art. 38. If a
conflict emerges between applicable legal rules, it can be resolved on the basis of guiding
principles such as:
Lex specialis derogate legii general – specific rule prevails over rules of general
application.
Lex posterior derogate priori – more recent law prevails over an inconsistent earlier
law.
If there is any hierarchy of sources at all, it would be between ‘normal’ sources and the
category of what are called ‘peremptory norms’ or jus cogens.
Customary international law (CIL)
CIL entails the recognition that practices of States on the international plane can create new
legal rules. Custom as a source of law gives prominence to the consent of States. There are
two elements of CIL:
Usus – a material element relating to the actual practice of States in their relations.
The notion of State practice encompasses the action or inaction of States in their
relations with each other, or in relation to recognized international actors. State
practice can be found in the judgments of national courts, the legislation of those
States and statements made by States. The actions of the State’s organs and agents,
therefore, may constitute relevant practice if the said action relates to the international
field. It is possible that States breach an existing rule as a way of establishing a new
rule. The is key the manner in which the inconsistent conduct is justified by the State
and whether it is accepted or rejected by other States.
Opinio juris – a subjective belief of States that such behavior is law. It is difficult to
determine this subjective belief. Sir Hersch Lauterpacht suggested establishing a
presumption that all uniform conduct by States was evidence of opinio juris unless the
contrary was proven. Opinio juris is important in order to avoid establishing patterns
of behavior where law-breaking becomes an essential method for law-making. There
needs to be a belief that a certain practice is obligatory by the existence of a rule of
law requiring it (NSCS, par. 77).
Specially affected State-doctrine – in the formation of a customary rule State practice,
including that of States whose interest are specially affected, should have been both extensive
and virtually uniform (North Sea Continental Shelf Judgment, par. 74). This doctrine has
often reflected that asymmetrical power relations between States, ensuring that the views of
the specially affected States are always taken into account when forming a new customary
rule.
