The UNCITRAL Working Group III turned squarely to designing permanent institutions : a standing appellate mechanism and a multilateral investment court (MIC).
In the end, states have the power to decide collectively what reforms to pursue, in what order and in what form. Individually, they will also have choice about which particular reform options to adopt.
The signing of an investment treaty involves a unilateral loss of sovereignty on the part of the host state, which is ultimately deemed necessary to attract foreign capital.