Enacting and developing international environmental law - Introduction to International Environmental Law - page 73

There is much debate over what the International Court of Justice meant to
express in its 2010 Pulp Mills judgment regarding the integration of the environ-
mental impact assessment (EIA) into general international law. The Court defi nes
international EIAs as 'a practice, which in recent years has gained so much accep-
tance among States that it may now be considered a requirement under general
international law to undertake an environmental impact assessment where there
is a risk that the proposed industrial activity may have a signifi cant adverse impact
in a transboundary context'. 26
Although the Court fails to expressly state that the transboundary EIA is
a general principle of law in the sense of Article 38(c), it does seem to actu-
ally consider it so. In the interpretation of most academics, however, the
International Court of Justice confi rmed that the transboundary EIA has
evolved into a principle of customary law. In any case, whether it is a general
principle or a norm of customary law, there is no doubt after this decision
that states are obliged to perform transboundary EIAs in cases where planned
activities pose a threat to the environment of other states or international
spaces.
There is a reason why the International Court of Justice is reluctant to apply
general principles of law and to discuss and defi ne them: the international
community of states is ready to observe the rules which it has created. In
concluding agreements states deliberately bind themselves legally to observe
their provisions. In this way, states are also contributing to the development
of international customary law, albeit tacitly. When the International Court of
Justice is called upon to resolve a dispute between states, it should be able to
convey that it is only applying the rules and principles to which the states
themselves have consented. Otherwise, it is much more likely that states
would fail to observe the Court's decisions in cases they lose, or that they
might become less willing to submit their disputes to the International Court
of Justice in the fi rst place. If the International Court of Justice were to appeal
expressly to general principles of law, it is likely that the states might fear that
the Court is taking too progressive an attitude to the development of interna-
tional law, rather than carrying out its basic duties, namely resolving discrete
disputes that threaten international relations. From the states' point of view,
the general principles of law are too general and indeterminate to constitute a
useful source of law that could be applied to settle real world disputes: in
theory, these general principles could allow the International Court of Justice
to apply norms to states that have given neither express (treaty) nor implied
(customary law) consent.
Secondary sources of law
International law can only be developed by states. Secondary sources of law,
such as the decisions of international courts of justice or committee reports of