After leaving school Walker earned arts and law degrees at the University of Sydney. He was admitted to the Bar in 1979 and became a silk in 1993. He quickly built a reputation as a formidable courtroom opponent, sharp wit and meticulous planner. Poetry, music and gardening are all important parts of Bret Walker's life. Credit:Andrew Meares Matthew Collins, QC, recalls being a junior lawyer when he first met Walker about 20 years ago, and feeling "incredibly intimidated". That is, before he walked into Walker's Sydney office. "It was a bit like Steptoe and Son," Collins laughs. "It was crammed full of artwork and memorabilia and objects of significance."

Like many barristers, Walker is something of a Renaissance man. He is a former chairman of the board of directors of Red Room Poetry, which commissions and nurtures established and emerging Australian poets. He told The Australian Financial Review five years ago that his favourite Australian poets were David Campbell and Robert Adamson and his favourite composers were Mozart, Bach, Bartok and Sibelius: "Mozart and Bach are very easily the two I could never do without." He is a keen gardener. But in his professional circles, he is known for having one of the sharpest legal minds this country has ever seen. "I've known him for in excess of 20 years," says fellow barrister Jack Rush, QC. "He's demonstrated himself to be in the top three or four barristers in Australia for two decades." Rush says Walker has an "uncommonly" good capacity to act at the highest levels in complex commercial law, human rights and international law, the High Court, and plenty of other courts in between. "I've been opposed to him a couple of times, and the scary thing about him is he conducts himself in a flowing, comprehensive and extremely analytical way from notes that are about the size of a matchbox." Just how good is he?

Really, really good. Last year it was reported Walker commands fees in the order of $25,000 a day. A small handful of Australia's top barristers now command in the order of $30,000 a day, and The Age and The Sydney Morning Herald has been told there is no reason to think Walker is any different. He represented former prime minister Kevin Rudd in the Royal Commission into the Home Insulation Program, successfully arguing that long-standing Cabinet secrecy rules be overturned and Rudd be allowed to give his evidence in full, rather than the royal commission being met with a "devastating truncation of the truth". Walker was one of the leading counsels in tobacco companies' ultimately unsuccessful fight against the Gillard government's plain packaging laws, and has represented the Finks Motorcycle Club in its fight against the validity of South Australia's anti-bikie laws. The Gillard government appointed Walker as the country's first Independent National Security Legislation Monitor. In a law lecture three years ago, Walker described how he essentially taught himself international law, remarking that before his appointment his reading in the highly specialised field had been "more for interest than for work".

"All that changed when the Security Council began issuing Chapter VII resolutions under the UN Charter compelling Australia and the other members of the United Nations to have and to enforce effective counter-terrorist regimes. Those of us in the field simply had to catch up with our colleagues in the rarified world of public international law." In 2017, Walker was hired by then deputy prime minister Barnaby Joyce to defend Joyce's political career amid dual citizenship claims. That move came as Walker was also representing Labor in its challenge to the constitutional validity of another Nationals MP, David Gillespie (Walker won for Joyce and lost against Gillespie). Says Collins: "In the modern era it's incredibly rare to have that breadth of skill." So how did Walker win the High Court case? The groundwork for that win was laid by Robert Richter, QC, who represented Pell at trial. Despite the County Court and Victorian Court of Appeal ruling against Pell, in the latter court the three judges were split two-to-one on one of the grounds of appeal. That opened the way for Walker to convince the High Court that the jury must have held some reasonable doubt about Pell's guilt, and to acquit him.