Jeffrey Sack is a founding partner of the law firm of Sack Goldblatt Mitchell LLP and is a leading member of the Canadian labour law Bar.  For 40 years, Jeffrey has represented trade unions and employees in labour law matters before tribunals and the courts, including the Supreme Court of Canada in Charter of Rights cases. In 1982, Jeffrey's standing in the profession was recognized in his appointment as Queen's Counsel.

Jeffrey is the founding president of the Canadian Association of Labour Lawyers (CALL), an organization of some 500 lawyers representing trade unions across the country, and a past president of the International Association of Labour Law Journals. He currently serves as co-director of the Canadian Labour Law Association, and as a member of the executive committee of the International Society for Labour & Social Security Law. 

Jeffrey has written on numerous issues in the labour law field. He is a co-author of the leading text on Ontario Labour Relations Board law and practice, and monographs on collective bargaining and arbitration in Canada. In 2010  the American Bar Association published in its Journal of Labor & Employment Law an article by Jeffrey on "Significant Distinctions between U.S. and Canadian Labour Law". Jeffrey is also the founder of Lancaster House, a leading publisher of materials on labour, employment and human rights law in Canada.

In 2005, Jeffrey received the Gerard Dion award from the Canadian Industrial Relations Association for outstanding contributions to labour relations in Canada. In 2009, he received the Outstanding Practitioner Award from the U.S.-based Labor and Employment Relations Association.

Jeffrey earned degrees in history and modern languages, and pursued post-graduate studies as a Woodrow Wilson Fellow in German literature and philosophy at Columbia University before embarking on a career in law.  He received his law degree from the University of Toronto and was called to the Ontario Bar in 1967.