Breaking with the Past 247
course of things— such as mounting an armed incursion into another state’s
territory in time of peace.
Th e American Secretary of State (and renowned lawyer) Daniel Webster
agreed, although he did insist that the emergency in question had to be ex-
treme. In words that are well known to international lawyers to the present
day, Webster cautioned that there must be “a necessity of self- defence, in-
stant, overwhelming, leaving no choice of means, and no moment delibera-
tion.” Th e important point for present purposes is the ac cep tance of the
principle of the overriding importance of the right of self- preservation (or
self- defense)—to the point that, when activated, it trumps the normal, ev-
eryday rights of states. (In the event, the dispute over the Caroline incident
was resolved amicably, largely in Britain’s favor.)
International Law as a Consensual System
One of the most important tenets of mainstream positivism was that inter-
national law is a system more or less consciously created by the states of the
world. First came the states, with their inherent, fundamental rights, and
then, from their initiative, came international law. International law is there-
fore, from this standpoint, a system in which the states of the world— which
are primordially free and independent— voluntarily choose to subject them-
selves to certain legal constraints. Th e basis of legal obligation, in the positiv-
ist scheme, is therefore the freely given consent of the parties to be bound
(i.e., the states).
Th e three variants of positivism were in disagreement as to just how this
consent comes about. According to the empirical school, it is expressed
through customary practice by the states collectively. According to the
common-will school, it arises from explicit agreement to the concluding of a
law treaty. According to the voluntarists, it occurs by way of self- restraint, or
autolimitation. Th e three schools were in agreement, though, on the funda-
mental thesis that consent is the basis of law.
A consensual picture of law directly implies a contractual perspective.
Th is was obvious enough in the case of written treaties. But for customary
law, too, there was venerable authority. It will be recalled that, in the seven-
teenth and eigh teenth centuries, the prevailing view, from Suárez and Gro-
tius onward, was that customary law is, in reality, a tacit agreement between