Rosanne has appeared as litigation counsel in British Columbia, Alberta and Ontario courts, including at the Supreme Court of Canada and other appellate courts. She successfully represented Lac Seul First Nation at the Supreme Court of Canada in Southwind v. Canada, a breach of fiduciary duty case resulting from the illegal flooding of reserve lands.
Her work in reconciliation and Treaty negotiations with the Crown has included representing shishalh Nation in a groundbreaking Foundation Agreement, and Tahltan Nation in the first ever consent-based decision-making agreements with British Columbia.
Rosanne has also been counsel to First Nations before regulatory bodies such as the National Energy Board (now Canadian Energy Regulator) and environmental assessment processes, including for the Northern Gateway Pipelines Project, the Trans Mountain Expansion Project and the Site C Dam.
She is also a former adjunct professor at the University of British Columbia Faculty of Law and a former guest lecturer at Simon Fraser University and the University of Victoria. She has published a number of articles on Aboriginal law issues, and is a regular speaker at conferences across the country.