What is the proper scope of the power of an arbitral tribunal to issue an order restraining a party from pursuit of parallel proceedings in a national court?

The proper scope of tribunal-ordered anti-suit injunctions to combat parallel proceedings has been subject to much debate. Some have argued that arbitrators’ use of the injunctions requires restriction, while others argue that existing conditions and limitations are sufficient. This paper provides an outline of the sources from which arbitrators are empowered to order anti-suit injunctions, the development of the injunctions through cases, and the recent European Court of Justice decision in Gazprom. It briefly touches on court-ordered anti-suit injunctions, and the implications of the Brussels I Regulation for tribunal-ordered anti-suit injunctions. It concludes that the scope of anti-suit injunctions does not require further restriction. Reasons for this conclusion include the 2006 amendments to the UNCITRAL Model Law; commercial reasons; the need to prevent conflicting decisions; and the nature of arbitration as arising from private commercial arrangements between parties