Mackness served as Dean of Management at the University of Manitoba from 1988 to 1995, and affiliated the department with the Fraser Institute. He became known for an abrasive management style, with one rival faculty member claiming he had created an "environment of hatred" at the department ("Winnipeg Free Press", 17 March 1995). He was also accused of intolerance in 1990 after mailing an internal letter on departmental renewal which included the line, "If we don't do something soon, we will all retire together and leave the place to Third World mathematicians" ("Winnipeg Free Press", 1 September 1990). His contract was not renewed in 1995, and his successor severed the department's affiliation with the Fraser Institute the following year.[http://umanitoba.ca/manitoban/1997-1998/1022/news.html]