Commonwealth of Australia v Verwayen [1990] 64 ALJR 540

Two navy ships collided during a combat exercise in 1964, and C, a naval officer, was injured as a result He did not sue for negligence as it was widely believed that armed forces members could not sue the government for the negligence of another member This belief changed in 1984, so the C promptly sued the government for the negligence of another member of the armed forces At first, the government had written back admitting negligence and said they would not rely on the statute of limitations, which would have resulted in the C being prevented from claiming due to time-constraints Less than a year later following reviewed policy, the government tried raising both defences (denying their fault and the limitation period)

• Had the government waived their defences through the letter they sent ten months prior to raising both defences?
• Would the doctrine of estoppel prevent the government from going back on their letter of assurances?

The High Court of Australia dismissed the Commonwealth's appeal by a majority of four to three. The government could not revive the defences it had previously assured the claimant it would not pursue. The majority did not speak with one voice on the doctrinal route: some judges relied on waiver, while others used estoppel to prevent the withdrawal. The decision should therefore not be attributed to a single comprehensive test accepted by every majority judge. It was a ruling on the consequences of the government's particular conduct in the litigation. Its treatment of assurances is comparative Australian authority and does not itself replace the distinct requirements of English promissory estoppel.

In this Australian decision, the Commonwealth could not withdraw assurances that it would not rely on specified defences. The majority reached that result through differing waiver and estoppel analyses. It is persuasive comparative material, not binding English authority establishing a single unified estoppel doctrine.

Verwayen illustrates the relationship between litigation assurances, reliance and the limits of changing position. Its fragmented reasoning makes it especially important to distinguish the result from any individual judge's theory. For UK undergraduate study it should be labelled as Australian comparative authority and contrasted with the English rules actually governing the problem. It does not justify stating that every abandoned defence is irrevocably lost or that all equitable estoppels share identical requirements.