Mark Oppenheimer is a practicing advocate and member of the Johannesburg Bar. He has appeared in the Supreme Court of Appeal and the Constitutional Court in a series of cases that seek to determine the boundary between freedom of expression and genuine hate speech.

Mark has authored submissions to Parliament on the Hate Speech Bill and to the UN Committee for the Elimination of Racial Discrimination on escalating racial tensions. He has also presented an oral submission to parliament on expropriation without compensation.

He coached the WITS moot team in the Oxford Price Media Law Moot competition. The team won the all-Africa Competition and went on to compete at the University of Oxford. He also served as an adjudicator in a series of moot competitions held at WITS.

He has been interviewed on eNCA, CNBC Africa and Cliff Central to discuss the bill of rights and the rule of law. Along with Gwen Ngwenya, he hosted the podcast Freedom Versus and he currently hosts the popular philosophy series Brain in a Vat. He is co-author of the Conversations about Philosophy Book Series.