Walker is the son of an Anglican minister. He is married to the Honourable Justice Sarah Pritchard, a judge of the Land and Environment Court of New South Wales.[2][3]
Walker was admitted to the New South Wales bar in 1979 and was appointed senior counsel in 1993. He was president of the New South Wales Bar Association from November 2001[5] to November 2003,[6] having been vice-president from 1996 to 2001.[4]
Walker is a member of the Council of Law Reporting for New South Wales, and was the editor of the NSW Law Reports from 2006 to 2018.[4] He is a patron of the State Library of New South Wales as a foundation senior fellow[7] and has been a member of the NSW Health Clinical Ethics Advisory Panel since 2003. He was governor of the Law Foundation of NSW from 1996 to 2007, and Special Commissioner of Inquiry for the NSW government into Sydney Ferries in 2007.[4] He was a foundation member and has been director of the Australian Academy of Law since 2007.[4][8]
He was a leading legal counsel representing tobacco companies in their unsuccessful fight against the Australian government's plain packaging legislation.[9][10][11]
In April 2011 Walker was appointed as the Independent National Security Legislation Monitor.[12] In 2015 Walker said that a proposed change to Australia's citizenship laws to give the Minister for Immigration the power to strip citizenship from people who support terrorism was unconstitutional. He said this was a misquote of the INSLM 2014 report by Prime MinisterTony Abbott.[13][14] In a 2015 interview with Lateline, Walker noted the Australian "habit of seeing a problem and passing a law about it".[15]
In 2018–19 Walker oversaw the South Australian Royal Commission into the Murray-Darling Basin. The report was damning of the maladministration that characterised the overseeing Murray-Darling Basin Authority, describing their decision-making as “incomprehensible” and “indefensible”.
In April 2020 Walker was appointed to a Special Commission of Inquiry to "investigate all matters and agencies involved with the Ruby Princess' departure and its return to Circular Quay on March 19".[17]
^See glass placard at Macquarie St entrance to the State Library of NSW, or see also: "Archived copy"(PDF). Archived from the original(PDF) on 24 July 2008. Retrieved 3 September 2008.{{cite web}}: CS1 maint: archived copy as title (link)