The Convention on the Settlement of Investment Disputes between States and Nationals of Other States (ICSID Convention, 1965) has been signed and ratified by over 150 countries (including Switzerland). ICSID has its own arbitration rules, according to which it administers arbitral proceedings. Swiss BITs offer investors the choice of institutional arbitration (i.e. under the rules and administrative support of ICSID) or ad hoc arbitration (i.e. under other rules of arbitration). If the parties to the dispute are unable to agree upon the applicable arbitration rules and the investor is unable or unwilling to submit the matter to ICSID arbitration, then the arbitration rules established by the United Nations Commission on International Trade Law (UNCITRAL) apply as a contingency solution.
Several international for a (UNCITRAL, ICSID etc.) are currently working on a precision of the arbitration mechanism. On April 1, 2014, the new UNCITRAL Transparency Rules were put in force. The rules apply in Investor-State Dispute Settlements, which are based on BITs concluded after April 1, 2014 and are executed according to the UNCITRAL arbitration rules. The UN Transparency Agreement, concluded in July 2014, extends the application of the UNCITRAL Transparency Rules for all signatory states to dispute settlements which are based on BITS concluded before April 1, 2014 or are treated by other arbitration rules than UNCITRAL arbitration rules (e.g. ICSID).
ICSID arbitration decisions may only be challenged under very limited circumstances stipulated in the ICSID Convention. Arbitration decisions based on other arbitration rules may be challenged under the terms of the 1958 Convention on the Recognition and Enforcement of Foreign Arbitral Awards (New York Convention) and/or national legislation.