Gilbert Marcus is a Senior Counsel at the Johannes Bar with a substantial practice in constitutional and administrative law.  He has the unusual experience of having conducted a human rights practice both under the repressive apartheid legal order as well as under the new democratic dispensation in South Africa since 1994.

Under apartheid, he spent 8 years practising public interest law at the Centre for Applied Legal Studies.  He did extensive work fighting political censorship and defending anti-apartheid activists charged with offences against state security, including treason.  With the advent of constitutional democracy, Gilbert has been involved in many of the major cases in the Constitutional Court.  These include a successful challenge to the constitutionality of the death penalty; the striking-down of laws that criminalised gay sexual relations; compelling the government to provide anti-retroviral drugs to pregnant mothers living with HIV and striking-down the laws which prohibited the formation of trade unions in the Defence Force.  He has appeared in the Constitutional Court in approximately 100 cases.  In the field of administrative law, he has argued the leading case in the Constitutional Court concerning the review of public procurement decisions and has argued many cases challenging regulatory approvals or disapprovals in diverse areas such as mining and telecommunications.  He has also appeared in courts in neighbouring territories, including Lesotho, Botswana and Swaziland.  He was admitted to the Bar of England and Wales in 1999.

Gilbert is a visiting professor of law at the University of the Witwatersrand.  He has written many academic articles and co-authored books on constitutional law and public interest litigation.