Does the current “spaghetti bowl” of dispute settlement provisions in RTAs, IIAs and the WTO require “effi ciency” promoting changes in the negotiation of IIAs? Most of the investment-related literature in recent years has focused on parallel or incoherent dispute settlement procedures within the area of investor-state proceedings. It has generally neglected the fact that dispute settlement provisions in IIAs (including investment chapters in RTAs) may interfere with the functioning of the multilateral trading system and its dispute settlement system-as well as the fastgrowing parallel structure of RTAs. The key concepts normally associated with this development may be summarized as including, amongst others: forum shopping, confl icting requirements, parallel proceedings, institutional overlap and divergent interpretation.1