Codelfa Construction v State Rail Authority of New South Wales (1982) 149 CLR 337

Codelfa was contracted to build tunnels for the Rail Authority of NSW, 24/7 so it would be finished in time. They believed the Rail Authority had permission to do so.
Part way into the contract, an injunction was granted against the work following complaints from the neighbours. Codelfa agreed to only work at day time.
Extra costs were incurred by this, and the State Rail Authority refused to pay, saying they didn’t act according to the contract.
Codelfa argued that either there was an implied term in the contract for this circumstance, OR that they should be paid on quantum meruit.

What is the Australian perspective on the parol evidence rule and implied terms?

Mason J: Rectification contains a term actually agreed on. Based on actual intention.
Implication (by contrast) is a term that was not agreed, but is said would have been there . Based on presumed intention.
Courts are reluctant to imply terms. In order to imply a term, it must give business efficacy, “go without saying”, doesn’t contradict other terms, etc
Parol evidence rule: outside evidence only accepted when face value is confusing
Outside evidence can resolve ambiguity but not raise it
A term cannot be implied because there are too many ways the parties may have chosen to resolve the issue
Frustration, however, can succeed.
Codelfa is entitled to be paid