If the court found in favour of Westpac, it would have the best of both worlds, with "the benefit of a lesser standard for a defence, but a higher standard for liability," he said.
Westpac could have entered a contract to limit its potential liability for a breach of mandate, "but it did not," he said.
In 2008, Westpac refused to act on instructions from Map to transfer some US$50 million that was held by about 20 shareholders in Prodem, a privately-owned Bolivian bank. Map was acting as the deposit agent for the investors, having put the money with Westpac in December 2006.
The Prodem investment had its rights assigned to another bank called Bandes during a transaction in early 2008, and when Westpac was called to transfer the funds, it refused to do so, saying "the money it was holding was in substantial part to be paid out to people or organisations who appeared not to be shareholders and it was unaware of the basis upon which they were to receive payment," the judgement said.
Westpac was unwilling to act on the instructions of the shareholders' attorney and invited Map to apply to the High Court, which ordered the bank to carry out the transfer and pay interest on the sum withheld and costs. That decision was upheld by the Court of Appeal last year.