Judicial Creativity in the Law of Maritime Delimitation

current rules appears to show that rules of law have been developed through the
case law of international courts and tribunals, independently of State practice and opinio
juris. A typical example is the concept of proportionality. The large role of proportionality
as an operational rule or as a test of equitableness cannot be explained from the viewpoints
of State practice and opinio juris. To a certain extent, the same is true of the effect to be
given to islands. While international courts and tribunals have developed the ‘half-effect’
solution concerning offshore islands, agreements giving half effect to offshore islands are
rare in State practice. It seems, therefore, that the courts’ solution of giving half effect to
offshore islands in the Anglo-French Continental Shelf, Tunisia/Libya and Gulf of Maine
cases is a novelty in this field. Such a solution can be regarded as an example of ‘judicial
creativity’.
Under Article 38(1) of the Statute of the ICJ, judicial decisions are merely subsidiary
means for the determination of rules of law. In the context of maritime delimitation,
however, it can be said that the ICJ and arbitral courts have been creating and developing
the law of maritime delimitation. The significant role of judicial creativity in the nature of
maritime delimitation may be explained by at least two reasons.
First, to achieve equitable results, there is a need to take various geographical and nongeographical
factors into account. Since one cannot expect there to be specific rules
regarding each and every factor to be considered, international courts and tribunals often
face potential lacunae in the law. Accordingly, within their compass, they need to develop
rules with regard to the effect to be attributed to those factors in the framework of equitable
principles.

Second, the Parties to a treaty seldom explain in the latter why and to what extent a
certain relevant circumstance has been taken into account when drawing a maritime
boundary. For this very reason, it is difficult to find evidence of opinio juris in State
practice. Here there is an inherent difficulty in identifying customary rules in the field of
maritime delimitation. Accordingly, it is hardly surprising that international courts and
tribunals have to rely mainly on judge-made law in this particular field.