he
Child.18 In addition, when ratifying, the
U.S. frequently includes many reservations and usually declares the
treaty to be non-self-executing.19
The second major source of international legal norms is customary
law. Under customary law, a nation is bound by certain legal norms even
if it has never signed a treaty containing those norms.
Basic Principles Regarding Custom. A custom is
formed by the "general and consistent practice of states followed by
them from a sense of legal obligation."20
For example, although there is no treaty on point, all nations are bound
by the following custom (a binding principle of international law): a
state may not enforce its domestic law within the boundaries of another
state without that state's consent.21 In
creating a custom, it is not enough for nations to consistently act in a
certain way. They must act that way from a sense of legal obligation (as
opposed, for example, to mere habit or courtesy).
The International Court of Justice considers the following factors in
determining whether there has been a general and consistent practice:
uniformity, consistency, and longevity.22
The first two factors are the most important. At times, a custom can be
formed quite quickly. For example, a 15-year period was deemed
sufficiently long for nations to adopt a custom of using a continental
shelf theory for claims to offshore oil and gas deposits.23 Other examples of legally binding customary
norms are that treaty obligations must be observed by ratifying
nations;24 a state may not detain an
individual indefinitely without charge or trial;25 and a state may not sanction human
A principle does not exist as a matter of customary law if there is
no agreement among states as to the scope and content of that
principle.27 For example, while the
Universal Declaration of Human Rights declares as a fundamental human
right the right to own and to not be arbitrarily deprived of property,
there is widespread disagreement about the exact contours of that right.
Protection of property rights is therefore not viewed as a principle of
A very important principle of customary law is that a norm is not
binding on a nation that consistently declares its dissent from the norm
during the norm's development.29 For
example, in the first half of the 20th century, Norway and the United
Kingdom battled over fishing rights off the Norwegian coast. Norway's
claim to exclusive fishing rights to certain ocean areas was based on
Norway's use of a unique cartography system different than that followed
by the rest of the world. Norway's consistent dissent from traditional
customary boundary rules and other nations' failure to adequately object
to Norway's interpretation meant that traditional boundary rules were
not binding on Norway as a matter of customary law.30
There is one exception to the principle that a nation can avoid being
bound by customary law by dissenting during development of the custom.
Some principles of customary law are viewed as so fundamental that no
dissent is permitted. These principles are known as jus cogens.31 The principles apply to all nations and cannot
be abrogated by treaty. They are considered peremptory norms.
Examples of jus cogens norms are found in the following provisions of
the Restatement (Third) of the Foreign Relations Law:
"A state violates international law if, as a matter of state policy,
it practices, encourages, or condones
"(b) slavery or slave trade,
"(c) the murder or causing the disappearance of individuals,
"(d) torture or other cruel, inhuman, or degrading treatment or
"(e) prolonged arbitrary detention,
"(f) systematic racial discrimination ...."32
Status of Custom Under U.S. Law. Custom, like a
treaty, is part of the "law of the United States" under the
Constitution's Supremacy Clause.33 Custom
is self-executing. No statutory authorization is required to make custom
effective. The only question is whether custom creates private rights of
recovery or merely obligations between governments.
One of the most famous examples of U.S. courts applying customary law
was the Paquete