McCusker was retained by a solicitor acting for a farming couple in August 1986 in a claim against the R & I Bank.

In March 1989, McCusker provided advice that the couple's claim had little chance of success, and if it was successful, the damages recovered were likely to be small.

Shortly after this the female half of the couple, Mrs Libby Smith, retained fresh counsel, including Daryl Williams QC, who was later an Attorney-General in the Howard Government from 1996 to 2003. He provided advice that was more positive in the couple's claim against the Bank. At this time Mrs Smith also convened a press conference criticising the advice of McCusker.

In 1995, the Smiths commenced legal proceedings against McCusker. Various courts within the WA legal system have found for both parties on numerous occasions since then. This includes a decision of the Full Court of the WA Supreme Court in 2000, which found that there was an arguable case to the effect that by reason of the negligence of McCusker, the Smiths had lost their grant of legal aid and their opportunity of recovering damages from the R&I Bank.

In the latest ruling, Chief Justice Wayne Martin rejected any notion that McCusker was negligent. He found that any reasonable barrister provided with the instructions given to McCusker would have advised the Smiths that they have no reasonable prospect of succeeding in their claim against the R&I Bank, which he described as "always hopeless and doomed to fail". Chief Justice Martin also found that the advice given by McCusker did not cause the Smiths to lose the benefit of legal aid in their claim against the bank.

McCusker, currently the chairman of the WA Legal Aid Commission and the WA Australian of the Year in 2010, was appointed as the next Governor of Western Australia last month. He will replace the current Governor Ken Michael in July.