But beyond that mundane question of law there may be two specific but important errors of law.
The arbitrators may have erred in their use of the phrase “common understanding and intention of the parties”.
That suggests that they erred in searching for the subjective intentions of the parties.
That is an extremely important matter, not always well understood.
It is very well established in this Court, and indeed in other ultimate appellate courts, that the question is not what contracting parties subjectively intended, believed or understood.
The question is, subject to special common law or equitable rules usually based on error or disadvantage, what each party by words or conduct would have led a reasonable person in the position of the other party to believe.
A departure from these principles by arbitrators is a serious matter.
They are not principles merely reflective of some quaint minor guide to construction.
They go to central substantive conceptions of the law of contract in the Anglo-Australian common law.
A second respect in which the arbitrators may have erred is their seeming reliance on post-contractual events as a guide to contractual interpretation.
Some see that as more controversial, but it is a very important question of law.