In real ity, today’s more than 240 IGOs seldom act alone. Often they carry out their
activities with the cooperation of other international or regional organ izations, as well
as with nonstate actors, including nongovernmental organ izations. Furthermore, they
are embedded in a structure of international law.
International law
International law developed thousands of years before con temporary international
organ izations. Treaties between city- states and communities can be found in Mesopo-
tamia; the Greeks and the Romans differentiated among diff er ent kinds of law,
including international law; and during the Middle Ages, the authority of the Catho-
lic Church developed canon law applying to all believers internationally. Yet, interna-
tional law is largely a product of Western civilization. The man dubbed as the father of
international law, the Dutch scholar Hugo Grotius (1583–1645), elucidated a number
of fundamental princi ples that serve as the foundation for modern international law
and international organ ization. For Grotius, all international relations are subject to
the rule of law— that is, a law of nations and the law of nature, the latter serving as the
ethical basis for the former. Grotian thinking rejects the idea that states can do what-
ever they wish and that war is the supreme right of states and the hallmark of their
sovereignty. Grotius, a classic idealist, believed that states, like people, basically are
rational and law abiding, capable of achieving cooperative goals.
The Grotian tradition argues that order in international relations is based on the
rule of law. Although Grotius himself was not concerned with an organ ization for
administering this rule of law, many subsequent theorists have seen an orga nizational
structure as a vital component in realizing the princi ples of international order. The
Grotian tradition was challenged by the Westphalian tradition, which established the
notion of state sovereignty within a territorial space (see Chapter 2). A per sis tent ten-
sion arose between the Westphalian tradition, with its emphasis on sovereignty, and
the Grotian tradition, with its focus on law and order. Did affirmation of state sover-
eignty mean that international law was irrelevant? Could international law under-
mine, or even threaten, state sovereignty? Would states join an international body that
could challenge or even subvert their own sovereignty?
International law and Its functions
International law consists of a body of both rules and norms regulating interactions
among states, between states and IGOs, and, in more limited cases, among IGOs,
states, and individuals. As in domestic jurisdictions, laws serve several purposes: set-
ting a body of expectations, providing order, protecting the status quo, and legitimat-
240 CHAPTER SEvEn ■ IGOs, InternatIOnaL Law, and nGOs