In Suez v Argentina (Case no ARB/03/17), a challenge to an ICSID arbitrator based upon her participation in an earlier award which was unfavourable to the challenger has been rejected.

The decision, which has been widely reported, contains a helpful exposition of the standard of proof which applies in relation to challenges to the impartiality or independence of arbitrators. It also demonstrates a strict approach to the timeliness of such challenges: in this case, a delay of less than two months was found to be sufficient to bar the challenge. The arbitrators who ruled on the point made clear that a challenging party should raise any objection as soon as he becomes aware of it. Even if the objection is made in summary form, it can (if raised in good time) be amplified at a later date.