Leanne MacMillan is a Research Representative for the Canadian Union of Public Employees, Atlantic Regional Office. Prior to this, from 2000-2008, Leanne was the staff lawyer for the Nova Scotia Nurses' Union. Leanne was the Chief Negotiator for Nurses in Nova Scotia in the last three rounds of bargaining in all sectors, including acute care, long term care and community care. She has also represented nurses with their professional associations.

Leanne practised with Pink Breen Larkin at its Halifax office from 1990-2000 where she provided legal advice and representation to unionized employees at arbitration, before labour relations boards and in the courts. She also represented a significant number of non-unionized employees in their dealings with employers. Further, Leanne has an expertise in pension issues and has presented frequently on issues of fiduciary responsibilities and governance. Leanne has also provided education on the duty to accommodate disabled workers.

Leanne is a member of the Canadian Association of Labour Lawyers and is one of the Nova Scotia Representatives to its Council.