Don has taught continuously for the last 15 years at several law faculties around the world. He was a full-time faculty member at the University of Western Ontario (London, Canada) and at the University of Saskatchewan (Saskatoon, Canada). He has held part-time positions at the law faculties of University of Ottawa (Canada), University of Stellenbosch (Cape Province, South Africa),the Université de Montpellier (France), Trinity Western University (Ottawa campus). He has taught in summer law programmes and given law lectures at Drake University (Des Moines, Iowa), Capital University (Columbus, Ohio), and the University of Ghana in Africa.

Don's teaching subjects include food and agriculture law, international trade law (WTO, EU and NAFTA), international trade law, the regulation of sustainable agriculture, trade in agricultural products, legal theory, legal ethics as well as the intellectual property and the environmental law of agriculture.

In 2003-2004, Don taught "The Regulation of Sustainable Agriculture" at the Faculty of Law, Common Law Section (in English and in French) and "Ethics and Public Policy" (with Dr. Janet Epp Buckingham) at Trinity Western University, Ottawa campus. In 2004-2005, Don is teaching "Torts" at the Faculty of Law, Common Law Section of the University of Ottawa (in English).