Sir Marcus Smith was called to the Bar in 1991 and took silk in 2010. He had a broad commercial and Chancery practice. He was appointed chair of the Competition Appeal Tribunal in 2009 and was chair of the Appeals Committee of the Human Fertilisation and Embryology Authority between 2015 and 2017. He became a High Court Judge in January 2017. Between 2019 and 2021, Marcus was Business and Property Courts Supervising Judge for the Midlands, Western and Wales. He relinquished that role on his appointment, in November 2021, as President of the Competition Appeal Tribunal. His term as President expired in November 2024.