A distinguishing characteristic of international arbitration hearings is that witness testimony is most often presented in writing in advance of the hearing, with the result that the witness portion of evidentiary hearings invariably consists almost entirely of cross-examination of fact and expert witnesses. There are advantages to presenting testimony in writing in advance, principally in reducing the time spent by arbitrators, counsel and others in hearings, with resultant savings in costs and time, as well as affording time for participants to prepare without having to try to anticipate last-minute testimonial surprises.

The ordinary practice with respect to witness statements is that parties receiving witness statements may elect or decline to cross-examine the witness, as may tribunal members. When, however, there is no oral examination of the witness before the tribunal, questions may arise as to the extent of the impact on the tribunal of the witness statement itself in the absence of any physical appearance of the witness at a hearing or any discussion of the content of the witness statement before the arbitrators.