He has appeared as counsel in many leading Bill of Rights/human rights and constitutional law cases. Internationally, he has worked on specific issues with many non-governmental organisations (such as Amnesty International, Lawyers Committee, the International Committee of Red Cross, Article 19). He has also appeared in official international forum and acted as a trial observer in the Asian region.
Professor Chan has served on many government/public and professional bodies, including the Bar Council, the Consumer Council, the Broadcasting Authority, the Press Council, the Administrative Appeals Board, the Municipal Services Appeals Board, Law Reform Sub-Committee on Privacy, Council of the Hong Kong Red Cross, and the Central Policy Unit of the Hong Kong Government. He served on the Consumer Council for 12 years and was the chairman of its Consumer Legal Action Fund for 6 years till 2010, during which time he oversaw, among other things, the test case involving the Lehman Brothers saga.
He is also the author of a weekly column in Ming Pao, a leading Chinese newspaper in Hong Kong for over 12 years since 2002 and, since 2008, served on the Civic Commission on Democratic Reform established by Mrs Anson Chan, the former Chief Secretary of Administration of the HKSAR. He joined Mrs Anson Chan again in 2013 to form a group known as 2020, the sole objective of which is to contribute to the political reform in Hong Kong.
In 1995, he was elected as one of the Ten Young Outstanding Persons in Hong Kong. In 1997, he received the Badge of Honour from the British Red Cross Society for his service. In 1999, he received the Human Rights Press Award. In 2003, he was appointed the first Honorary Senior Counsel. In 2011, he completed the Management and Leadership in Higher Education Program at Harvard University.