234 A Positive Century (1815–1914)a right to declare the treaty rescinded. But that is not so for a law- treaty,
which remains in force in the face of a breach and is terminable only by the
joint will of all the parties. Here too, the analogy with legislation is appar-
ent. A breach of a statute by one person (such as the commission of a crimi-
nal off ense) does not absolve other persons from obeying the law them-
selves. In other words, the parties to a law- treaty are “locked in” once the
treaty is concluded (i.e., once the rule of law in question is “enacted”), but
parties to a contract- treaty are not.
Th e second major distinctive feature of the common-will variant of posi-
tivism was its insistence upon a rigid separation between international law
and national law. Triepel was again the leading fi gure here, with Anzilotti
lending strong support. Th is belief has been labeled as “dualism” by inter-
national lawyers, for obvious reasons. Th e rationale behind it was simple.
Th e two systems of law (national and international) were held to emanate
from quite distinct sources. National law arises from the unilateral will of
a given state, typically articulated in a written constitution or basic law of
some kind. International law, in contrast, arises out of the common will of a
plurality of states, which is both diff erent from and superior to the individ-
ual wills of the contracting states. Th is distinctiveness of sources is rein-
forced by a diff erence in the fi eld of application of the two kinds of law. Na-
tional law is directed at the conduct of private parties, while international
law governs the mutual relations between states as such.
An interesting challenge to this dualist picture is a situation in which a
state is prohibited by its national law from doing something that is required
of it by international law. An example would be a treaty that required extra-
dition of any person, regardless of nationality, matched against a constitu-
tional ban on the extradition of nationals to foreign states. When the extra-
dition of a national of the state is sought, a direct confl ict between the two
obligations occurs. Which law prevails in such a case? Anzilotti was ready
with an answer to this. He contended that, strictly speaking, the apparent
contradiction is only an illusion. Th e reason is that, within each of the two
systems— considered in de pen dently of one another— there is no contradic-
tion. International law unambiguously requires one outcome, while national
law, equally unambiguously, requires another. Th ere is therefore no clash
between the two systems of law, as such.