Where a building, engineering or mining contract empowers a proprietor to determine the value of variations 'in its sole discretion', and the valuation involves discretionary judgment rather than a mechanical exercise, the valuation can only be challenged on the grounds that the valuer failed to act honestly, bona fide and reasonably, or that the valuation was not in accordance with the contract, or that the valuer acted on a wrong principle of law or the valuation was entirely erroneous. An arbitrator whose powers are limited to resolving disputes under the contract (without express power to 'open up, review and revise') cannot simply disagree with the valuation and substitute his own. However, if the valuation is properly set aside on those limited grounds, the arbitrator may substitute his own valuation.
The full text is available to signed-in members, including the 27 later cases that cite this judgment.
2 of the 27 citing cases carry a classified treatment. How each court treated it is available to signed-in members.