80 Law and Morality Abroad (to ca. ad 1550)Customs of States
With the ius gentium now seen as, eff ectively, a sort of secondary or deriva-
tive aspect of natural law itself, an important break was made with the old
Roman-law ius gentium. By being so tightly chained (so to speak) to natural
law, the ius gentium was deprived of its ability to evolve in de pen dently. Th at
meant that it was now less well equipped to play what had been its original
role in Roman law: the devising of a set of common practices, animated by
a rough- and- ready, commonsense equity, to deal with concrete, practical
problems as they arose. Th at did not mean that the search for solutions to
practical problems of international relations came to an end. Far from it. It
only meant that the solutions devised were not neatly pigeonholed by aca-
demics and theologians into the neat compartments of “natural law” and
“ius gentium.” Th ey existed on the margins of medieval legal consciousness—
but nonetheless eff ectively for that.
It would appear that no precise label was ever given to these various ad
hoc practices. Th ey were basically forms of customary law. In its medieval
usage, customary law referred to lawmaking from below rather than above—
that is, to lawmaking eff ectuated by the people of a country on their own
collective initiative, through day- to- day practice, as opposed to law that was
handed down from above, by monarchs or parliaments. In international af-
fairs, the position was similar, with various regular practices growing up
and gaining hold over time. Th e actual status of these practices as law was
not very clear. But so long as they were either widely observed de facto or
else enforced somehow or other by some authority or other, there seemed no
reason to deny that they were laws for practical purposes, if perhaps not in
strict theory. In all events, three areas illustrate this pro cess in action with
par tic u lar clarity: maritime law, the law on the conduct of war, and the law
merchant.
Maritime Law
Bringing order to the seas has always been problematic and remains so to
the present day. But the earliest important progress in this direction was
achieved in the Middle Ages. It was largely the seafaring communities them-
selves that are to be credited for this. Several bodies of law were devised