Sir Mark Hedley practiced as a barrister for many years in Liverpool specialising in the law that affected those at the bottom of the social hierarchy. He was appointed a full-time Circuit Judge in 1992 and from 1997 to 2002 was responsible for judicial training in family law. As a High Court Judge he presided over many cases which attracted media reporting and comment. He also had management responsibility for other judges both in Wales and then in Greater London.
In May 2016 it was announced by the Home Secretary that Sir Mark has been appointed to a panel of experts who will undertake an independent review into the application of Sharia Law in England and Wales.