The ICSID Convention Rules and Regulations were adopted in 1967, and the Additional Facility Rules in 1978.
There have been four rounds of rule changes following the adoption of the rules, the last of which entered into force in April 2006. Those amendments incorporated important improvements to the system, including:
strengthened disclosure requirements for arbitrators (Arbitration Rule 6(2), Article 13(2) of the Arbitration (Additional Facility) Rules);
a provision on the possibility to hold open hearings (Arbitration Rule 32(2), Article 39(2) of the Arbitration (Additional Facility) Rules);
expanded transparency provisions to publish awards as soon as possible (Arbitration Rule 48(4), Article 53(3) of the Arbitration (Additional Facility) Rules);
the opportunity for non-disputing parties to file submissions (amicus curiae briefs) (Arbitration Rule 37(2), Article 41(3) of the Arbitration (Additional Facility) Rules); and
the possibility for a respondent to obtain an early dismissal of a case due to manifest lack of legal merit (Arbitration Rule 41(5), Article 45(6) of the Arbitration (Additional Facility) Rules).
These amendments have had far-reaching effects on the practice of investment arbitration, and have been widely emulated in the rules of other arbitral institutions, in newly negotiated investment treaties, and in parts of the Mauritius Convention and the UNCITRAL Rules on Transparency in Treaty-based Investor-State Arbitration.