Introduction The Max Planck Encyclopedia of International Law defines 'mass claims' as compensation sought when a large number of parties have suffered damages arising from the same diplomatic, historic, or other event. 1 In that sense, mass claims have existed for a long time. Given the diplomatic and historical nature of the term, mass claims have existed primarily on the public international law landscape, leaving little space for private international law interests to fall within its scope. However, given the relatively recent grafting of private international dispute settlement into the public international law stem through investment arbitration, there is a new-found room for mass claims.