Jonathan has practiced as a member of the Johannesburg Bar since 2012. He completed his pupillage after having worked for the AIDS Law Project (and its successor SECTION27) from 2002 to 2011. Prior to that, he clerked for Justice Kate O’Regan at the Constitutional Court.

Jonathan served as a member of the Medicines Control Council (now SAHPRA) from 2009 to 2011, and as a member of the Expert Advisory Group to the Geneva-based Medicines Patent Pool from 2011 to 2019.

He holds degrees in architecture and law from Wits University, and a masters in law from the University of Toronto, which focused on international trade law and access to medicines.

Jonathan appears regularly in the High Court, ordinarily on his own or with a junior, in a wide range of matters. As lead counsel, he has appeared twice in the Supreme Court of Appeal, and four times in the Constitutional Court. He has also appeared in the Court of Appeal in Botswana, and the High Court and Supreme Court of Eswatini.

Jonathan appeared as lead counsel in the following reported cases:

• Blind SA v President of the Republic of South Africa and Others 2025 (7) BCLR 757 (CC)
• Commissioner for the South African Revenue Service v Medtronic International Trading S.A.R.L 2025 (2) SA 337 (CC)
• Blind SA v Minister of Trade, Industry and Competition and Others 2023 (2) BCLR 117 (CC)
• Commissioner for the South African Revenue Service v Medtronic International Trading S.A.R.L 2023 (3) SA 423 (SCA)