Procedural Aspects of Shared Responsibility in the WTO Dispute Settlement System

An international actor is responsible under international law when an act attributable to it causes a breach of an obligation by which it is bound. Sometimes third party actors can share elements of that responsibility. At the one end of the spectrum, a third party can fully share the responsibility of the primary party. More modestly, the acts of a third party can have a bearing on the responsibility of the primary party without this necessarily impacting on its own responsibility. There are two main ways in which this can happen: the first is when the same act is attributable both to the primary party and to the third party; the second is when the act of the primary party and a different act of the third party together cause the breach of the obligation of the primary party. This article looks at how, thus defined, third parties sharing elements of responsibility with a primary actor are taken into account in WTO dispute settlement proceedings.