Leslie practised employment and labour relations law with Miller Thomson LLP and served as vice-president of Magna International. Thereafter she held executive positions in the Ontario Public Service-in the Pay Equity Commission, in Management Board of Cabinet, and in the Ministry of the Attorney General. In 1993, Leslie was appointed Assistant Deputy Attorney General for Ontario, responsible for civil and constitutional law, victims of crime issues, development of Mandatory Mediation in Ontario (Rule 24.1) and the Dispute Resolution Office.
In 1999, she left to establish Leslie H. Macleod & Associates.
Since then, Leslie has undertaken assignments across Canada and internationally. Leslie's contributions to the field of Alternative Dispute Resolution (ADR) have received widespread recognition. She has done pioneering work in the mandatory mediation of lawsuits, the resolution of complex matters, and the design and evaluation of ADR processes and systems.
In 2019, after more than 20 years as an Adjunct Professor, Leslie retired from teaching and from her position as Co-Director of the LL.M. in ADR Program at Osgoode Hall Law School. She continues to provide a full range of conflict resolution services through her firm.
Leslie is a Member of the Law Society of Upper Canada, the Canadian and Ontario Bar Associations, and numerous dispute resolution organizations. She is a member and former Chair of the Ontario Bar Association - ADR Section and a former Board member of the Society of Professionals in Dispute Resolution. She is also a member of Toronto's Local Mandatory Mediation Committee.
Leslie has received the following awards in recognition of her work in the field of Conflict Resolution:
- In 1999, the Ontario Mandatory Mediation Program received the Significant Practical Achievement Award from the Center for Public Resources Institute for Dispute Resolution (New York, NY);
- In 2003, Leslie was a recipient of the Federal Head of Public Service Award for Collaborative Working Relationships for her contributions to the ADR Program of the Immigration Review Board;
- In 2005, she was selected for the Ontario Bar Association Award for Excellence in Alternative Dispute Resolution for her accomplishments in ADR; and
- In 2011 and again in 2019, she received the Osgoode Professional LL.M. Teaching Excellence Award in recognition of her teaching at Osgoode Hall Law School.