Mark S. Winfield is an assistant professor in the Faculty of Environmental Studies at York University. He was policy and program director with the Pembina Institute from 2001 to 2007, and director of research at the Canadian Institute for Environmental Law and Policy from 1992 to 2001. He has written numerous articles on environmental law and policy, and testified at the Walkerton Inquiry as an expert witness on Ontario environmental law and policy affecting drinking water quality.