During the summers, she worked full time as a maritime surface officer with the Royal Canadian Navy, Naval Reserve. Justice Leonard clerked with the Alberta Court of Appeal and the Court of Queen’s Bench in Calgary. She was called to the bar in 2003 and joined the firm of Borden Ladner Gervais LLP in Calgary.
In 2006, Justice Leonard joined the Canadian Armed Forces as a legal officer. In 2009, she was deployed to Kabul, Afghanistan, where she worked alongside American military lawyers as a legal mentor to the Afghan National Army. In 2012, Justice Leonard returned to the Naval Reserve and began full-time employment with the Public Prosecution Service of Canada (PPSC). In 2017, she became the Deputy Chief Federal Prosecutor for the Alberta Region of the PPSC.
Inspired by her deployment to Afghanistan, Justice Leonard completed her LL.M. in 2014 at the University of Alberta with a focus on international law and post-conflict peacebuilding. For the last three years, she helped coach the University of Alberta Laskin Moot team.