Using res judicata to resolve jurisdictional conflicts between WTO and regional trade agreements’ dispute settlement mechanisms

Samson Muchiri

Abstract

The WTO has a renowned dispute settlement body, distinguished from
other dispute settlement bodies by its compulsory and exclusive jurisdiction.
However, regional trade agreements provide for rights and obligations
similar to those guaranteed by the WTO thus, causing material jurisdictional
overlaps between the WTO institutions and regional dispute resolution
institutions. Potentially, a State aggrieved by measures that contravene
rights or obligations within such overlaps has two alternative fora for
dispute resolution. Where the regional trade agreement dispute resolution
mechanism resolves the dispute first, the compulsory and exclusive nature
of the WTO jurisdiction allows the matter to be re-determined at the WTO
level, causing jurisdictional conflicts and duplicative proceedings.

Although it is an established principle in customary international law, res
judicata is not provided in any of the instruments guiding the jurisdiction of
the WTO dispute settlement system. The jurisprudence of WTO Panels and
the Appellate Body are also thin on this matter. Seemingly, the inclination has been to exercise the compulsory and exclusive jurisdiction, without regard
to other existing fora. This paper therefore suggests clear recommendations
to be employed in widening the existing WTO jurisprudence on res judicata
as a solution to jurisdictional conflicts. In doing so, this paper further
acknowledges the possible criticisms against res judicata in WTO dispute
settlement and provides possible solutions to these challenges to ensure
the peaceful and harmonious coexistence of the WTO dispute settlement
mechanisms vis-à-vis those of regional trade agreements. Using the South
American region as an example, this paper enunciates the jurisdictional
overlaps and proposes the application of res judicata by the WTO dispute
settlement mechanisms in judicial restraint