His Honour was admitted in NSW, Qld and in the High Court in 1995. He worked as a solicitor in NSW for four years before moving to live on the Sunshine Coast, continuing to work as a solicitor and partner of a law firm there until 2007. In 2007, His Honour went to the Bar and practised primarily in Family, Crime, Civil litigation and Alternate Dispute Resolution.
Away from the Law, Judge Middleton volunteered in Cambodia for approximately 4 years as a teacher in the far North West of Cambodia. He also lectured and was a tutor in Business and Law at the Sunshine Coast University. Judge Middleton is an avid runner and has completed many marathons including an ultra-marathon in the Sahara Desert over 6 days. He competes in triathlons and has completed many events including the Australian Iron man at Port Macquarie.