Health Canada is threatening to prosecute a Vancouver physician who says he has successfully using the Amazonian plant medicine ayahuasca to treat addiction. In a two-page letter sent last week, Johanne Beaulieu, director of Ottawa's Office of Controlled Substances, reminded Gabor Maté that possession of ayahuasca is illegal under Canada's Controlled Drugs and Substances Act. The letter warned that unless he immediately ceased the treatments, the RCMP would be notified. Dr. Maté, a family practitioner who specializes in addiction, said he will reluctantly comply with the order.