Malcolm Mercer teaches legal ethics as an adjunct professor at Osgoode Hall Law School. As general counsel to McCarthy Tétrault LLP, he advised the firm and its lawyers on matters of legal ethics and professional responsibility. Now retired as a partner from McCarthy Tétrault LLP, he continues to provide advice and expert opinion in these areas. He is an emeritus Treasurer of the Law Society of Ontario. He is a member of the Hearing and Appeal Divisions of the Law Society Tribunal. When he was a bencher, he chaired the Law Society's Professional Regulation Committee and its' Advertising and Fee Arrangements Working Group and co-chaired its' Alternative Business Structures Working Group. He is a past chair of the Ethics and Professional Responsibility Committee of the Canadian Bar Association, was a member of the CBA Task Force on Conflicts of Interest and is a member of the National Committee on Accreditation of the Federation of Law Societies of Canada.