Sandison graduated from the University of Aberdeen in 1989, with a Bachelor of Laws degree and then from the University of Edinburgh with a Diploma in Legal Practice. He obtained a Diploma in Forensic Medicine from the University of Glasgow. Sandison obtained a master's degree in 1991 and a PhD in 1994, both from the University of Cambridge. He trained with Scottish solicitor's firm Brodies before becoming an Advocate at the Faculty of Advocates in 1996. He became a Queen's Counsel in 2009. It was announced on 4 February 2021 that Sandison had been appointed as a Senator of the College of Justice.[1] He was installed as a Senator of the College of Justice at a ceremony in the Court of Session on 23 February 2021, taking the judicial title of Lord Sandison.[2]