The ambiguity gateway from Codelfa remains a precondition to admissibility of extrinsic evidence of surrounding circumstances in contractual construction in Western Australia, following the pronouncement in Western Export Services Inc. The AG of Belize approach assimilating implication with construction has not been adopted in Australia, and the BP Refinery five-criteria test continues to govern implication of terms in fact. A proposed construction that requires reading words into a contract that are not there may cross the boundary into implication and must satisfy the stricter BP Refinery requirements.
The full text is available to signed-in members, including the 17 later cases that cite this judgment.