In
law,
custom, or
customary law consists of established patterns of behaviour that can be objectively verified within a particular social setting. Generally, customary law exists where
- a certain legal practice is observed
- the relevant actors consider it to be law (opinio iuris).
Customary law and codification
The modern
codification of
civil law developed out of the
customs, or
coutumes of the
middle ages, expressions of law that developed in particular communities and slowly collected and written down by local
jurists. Such customs acquired the force of law when they became the undisputed rule by which certain entitlements (
rights) or
obligations were regulated between members of a community.
International law
In
international law,
customary law refers to the
Law of Nations or the legal norms that have developed through the customary exchanges between
states over time, whether based on
diplomacy or aggression. Essentially, legal obligations are believed to arise between states to carry out their affairs consistently with past accepted conduct. These customs can also change based on the acceptance or rejection by states of particular acts. Some principles of customary law have achieved the force of
peremptory norms, which cannot be violated or altered except by a norm of comparable strength. These norms are said to gain their strength from universal acceptance, such as the prohibitions against
genocide and
slavery. Customary international law can be distinguished from
treaty law, which consists of explicit agreements between nations to assume obligations. However, many treaties are attempts to codify pre-existing customary law.
Customary law within contemporary legal systems
Customary law may also be relevant within
jurisdictions following another legal tradition such as
civil law in fields or subfields of law where no legislative enactment exists. For example, in
Austria, scholars of
private law often claim that customary law continues to exist, whereas
public law scholars dispute this claim. In any case, it is hard to find any practically relevant examples.
See also
Law | International law
Gewoontereg | Sædvaneret | Gewohnheitsrecht | Derecho consuetudinario | Coutume | מנהג במשפטים | Gewoonterecht | 慣習法 | Coutume