naval custom evolved into the law of the sea over several hundred years. Sometimes
customs become outmoded. For example, the three- mile territorial extension from
shore was established because that was the distance a cannonball could fly. Eventually,
law caught up with changes in technology, and states were granted a 12- mile exten-
sion of territory into the ocean. But even then, a period of conflict between advocates
of the new and supporters of the old often follows. Occasionally, customs change
more rapidly. Witness the norms and prohibition against genocide developing in just
one generation, as discussed in Chapter 10. Furthermore, not all states participate in
the making of customary law, let alone assent to the customs that have become law
through European- centered practices. And the fact that customary law is initially
uncodified leads to ambiguity in interpretation.
International law also arose from treaties, the dominant source of law today. Trea-
ties, explic itly written agreements among states, number more than 25,000 since 1648
and cover myriad issues. When deciding cases, most judicial bodies look to treaty law
first. Treaties are legally binding: only major changes in circumstances give states the
right not to follow treaties they have ratified.
Authoritative bodies have also formulated and codified international law. Among
these bodies is the UN International Law Commission, composed of prominent inter-
national jurists. That commission has codified much customary law: the Law of the
Sea (1958), the Vienna Convention of the Law of Treaties (1969), and the Vienna
Conventions on Diplomatic Relations (1961) and on Consular Relations (1963). The
commission also drafts new conventions for which there is no customary law. For
example, laws on product liability and on the succession of states and governments
have been formulated in this way and then submitted to states for ratification.
Courts are also sources of international law. Although the International Court of
Justice (ICJ) has been responsible for some significant decisions, the ICJ basically is a
weak institution for several reasons. First, the court actually hears very few cases;
between 1946 and 2015, the ICJ has had 161 contentious cases brought before it and
has issued only 26 advisory opinions, although since the end of the Cold War, its case-
load has increased. Ever since the small developing country of Nicaragua won a judi-
cial victory over the United States in 1984, developing countries have shown greater
trust in the court. Although procedures have changed to speed up the lengthy pro cess,
the court’s noncompulsory jurisdiction provision still limits its caseload. Both parties
must agree to the court’s jurisdiction before a case is taken. This stands in stark con-
trast to domestic courts, which enjoy compulsory jurisdiction. A person accused of a
crime is compelled to judgment. No state is compelled to submit to the ICJ.
Second, when cases are heard, they rarely deal with the major controversies of
the day, such as the war in Vietnam, the invasion of Af ghan i stan, or the unraveling of the
Soviet Union or of Yugo slavia. Those controversies are generally po liti cal and outside
the court’s reach, although interstate boundary disputes are major issues on the court’s
242 CHAPTER SEvEn ■ IGOs, InternatIOnal law, and nGOs