Customary International Law

Question 1

Customary international law

Answer 1

Results from a general and consistent practice of states that they follow from a sense of legal obligation

Question 2

Two elements of customary international law

Answer 2

• State practice

- Opinio juris sive necessitatis

Question 3

North Sea Cases 1969 on custom

Answer 3

“Not only must the acts concerned amount to a settled practice, but they must also be such, or be carried out in such a way, as to be evidence of a rule of belief that this practice is rendered obligatory by the existence of a rule of law requiring it”

Question 4

Where are the sources of IL listed?

Answer 4

Art 38(1) ICJ Statute

Question 5

What is the problem with opinio juris?

Answer 5

That if you want to change the rule is to breach it and see if other states agree with what you’ve done

Question 6

North Sea Cases 1969 on basic principles of transforming evidence into custom

Answer 6

“The states concerned must feel that they are conforming to what amounts to a legal obligation. The frequency or even habitual character of the acts is not in itself enough. There are many international acts… which are performed almost invariably, but which are motivated only by considerations of courtesy, convenience or tradition, and not by any sense of legal duty.”

Question 7

Kosovo Advisory Opinion, 2010 on custom

Answer 7

Declarations of independence not prohibited by international law, as proven by State practice in 18th, 19th and 20th centuries

Question 8

Jurisdictional Immunities of the State, 2010 on custom

Answer 8

State practice is to be found in the judgments of national courts faced with the question whether a foreign State is immune, the legislation of those States which have enacted statutes dealing with immunity, the claims to immunity advanced by States before foreign courts and the statements made by States

Question 9

Al Saadoon v SoS for Defence 2015

Answer 9

I: Whether there was an obligation to investigate allegations of that a person transferred into the custody of Iraq by UK forces was being detained in violation of Art 5?
H: No general state practice accepted as law that all credible allegations of inhuman or degrading treatment by state officials must be investigated

Question 10

Serdar Mohammad v SoS for Defence 2015

Answer 10

I: Whether there was a rule of CIL permitting indefinite detention by an outside power involved in a third country in a non-international armed conflict?
H: Not enough state practice, also mentioned that the requirements of practice may not be as high when it comes to the emergence of a principle or a rule reflecting the laws of humanity, i.e. international humanitarian law

Question 11

What is the unique thing about customary IL?

Answer 11

Once it’s taken to have developed, it binds all States irrespectively of whether or not the practice of a particular State has contributed to the development of that customary law

Question 12

Anglo-Norwegian Fisheries Case 1951

Answer 12

I: Whether Norway’s method of drawing the baseline from which it measured its territorial sea was legally acceptable?
H: The persistent objector rule laid down, Norway always opposed the ten-mile rule so exempt

Positive obligations require greater consistency in state practice than passive obligations

Question 13

The persistent objector rule

Answer 13

“In principle a state that indicates its dissent from a practice while the law is still in the process of development is not bound by that rule even after it matures”

Question 14

Why is local custom problematic?

Answer 14

Because it accepts that international law can be different in different regions of the world

Question 15

Asylum Case 1950

Answer 15

I: Can the Colombian government offer asylum under local custom?
H: No such local custom exists sufficient to be binding at international law. The Court held that the party which relies on a custom of this kind has the burden of establishing that the custom exists in such a way that it has become binding on the other party, through constant and uniform usage of the states

Question 16

Rights of Navigation 2009

Answer 16

There was a local custom between Costa Rica and Nicaragua
“For the Court, the failure of Nicaragua to deny the existence of a right arising from the practice which had continued undisturbed and unquestioned over a very long period, is particularly significant”

Question 17

General principles of law

Answer 17

A reservoir of principles which an international judge is authorised by Art 38 to apply in an international dispute, if their application appears relevant and appropriate in the different context of international relations

Question 18

Art 59 ICJ Statute

Answer 18

Non-binding and non-precedential character of the decisions of the ICJ

Question 19

Nuclear Weapons Advisory Opinion 1996

Answer 19

GA resolutions, even though not binding, may sometimes have normative value - in certain circumstances, they can provide evidence for establishing the existence of a rule or the emergence of an opinio juris

Question 20

Art 25 UN Charter

Answer 20

UN Members have to accept and carry out decisions of the Security Council

Question 21

North Sea Continental Shelf on custom and treaties

Answer 21

The treaty provision, in order to give rise to the custom, must be capable of general application and must be intended to be the basis for future state practice, as well as being supported by opinio juris and acts of state practice by non-parties to the treaty

Question 22

Gulf of Maine on customary international law

Answer 22

It is ideally suited to the development of general principles and it’s always available to fill the void if treaty fails