In Ambiente Ufficio S.p.A. and others v Argentine Republic, an ICSID tribunal held that it had general jurisdiction over a multi-party claim commenced by 90 distinct Italian nationals against Argentina in respect of harm said to result from Argentina’s default and later partial restructuring of its sovereign debt. It might at first blush appear that the tribunal’s willingness to admit a 90-party claim is an affirmation of the favourable approach to so-called “mass claims” taken by its “sister tribunal” in Abaclat (and others) v The Argentine Republic.