F Ltd v M Ltd [2009] EWHC 275 (TCC), [2009] All ER (D) 260 (Feb)
The existence of a dissenting opinion on a point of law or fact, arising in connection with an issue that has been pleaded or dealt with by the parties in argument, will be irrelevant to any application under s 68 of the Arbitration Act 1996. The decision of the Arbitral Tribunal on such a point, albeit by a majority rather than unanimously, could not be challenged for serious irregularity in such circumstances.
However, a comment or observation in a dissenting opinion, to the effect that an important point has been decided by the majority without reference to the parties, will be a factor to which the court will attach weight in dealing with an application under s 68 (and may have considerable weight, although it is unlikely that it could, on its own, prove determinative).
Where an argument raised by the dissenting arbitrator has plainly been considered and rejected by the majority, even if it is an argument that the parties did not themselves raise, it may be difficult to say that there was a substantial injustice, since (regardless of how it arose) the argument will have been considered and rejected by the majority.