Originally from American Review of International Arbitration - ARIA

Until relatively recently, parties to international arbitration agreements had no recourse to arbitration to preserve the status quo, conserve assets or evidence, or seek other provisional relief until a tribunal had been established in a particular case – a process that, in the best of circumstances, took weeks after submission of a “request for arbitration” or “notice of arbitration.” One of the principal advantages of international arbitration – party participation in the selection of the decision-maker – precluded the possibility of immediate relief prior to the constitution of a tribunal.  To obtain provisional measures in such circumstances, parties were required to resort to national courts. 
And thus international disputes that the parties agreed to have resolved by international arbitrators rather than national courts were sometimes effectively decided by a national court’s decision on the request for interim relief.  If the court denied the request for interim relief, the applicant might decide that there was no point in commencing or continuing with the arbitration – either because it had no realistic possibility to obtain an effective remedy if it ultimately prevailed in the arbitration or because it was persuaded by the national court’s skepticism about the likelihood it would succeed on the merits of its underlying claims (in most jurisdictions, national courts are required to make some merits evaluation on a request for interim relief).  Similarly, if the national court granted the request and commented favorably on the merits of the applicant’s case, the responding party might seek to settle the matter.  In such circumstances, the national court had effectively decided the case: international arbitration delayed was quite literally international arbitration denied. 
In response to these concerns, and greatly facilitated by universal acceptance of e-mail as a reliable means of communication, over the last ten years most major arbitration institutions have implemented rules and procedures to provide parties with an “emergency arbitrator” to decide requests for interim or conservatory relief prior to appointment of the arbitral tribunal.  In such cases, the parties surrender their interest in selection of the decision-maker to the institution in order to resolve disputes too urgent to await a regularly constituted tribunal. This remarkable innovation has now become standard in rules governing international arbitrations.  As a relatively new development, some of the tensions between theory and reality in emergency arbitration are only now coming into focus.