Arbitration has become the most common method for the investor-state disputes settlement (ISDS), and under the current system of ISDS disputes are not settled by a single adjudicative body, instead investment arbitration is conducted by a number of tribunals. The fragmented nature of the system of ISDS and International Investment Law (IIL) coupled with the lack of a regulatory body has given rise to certain concerns of illegitimacy such as the issues of regulatory chill, lack of transparency, consistency a