In June 2001, the majority of the Supreme Court of Canada cited the precautionary principle¹ as a principle of international law and policy and concluded that municipal power to regulate pesticides is consistent with the principle.² This decision marked a decade of growth for the precautionary principle in Canada.

The precautionary principle states that where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation.³ Globally, the earliest explicit reference to the precautionary principle is found in the "Vorsorgenprinzip" of West German legislation of the early 1970s.⁴ The earliest international agreement to use an explicit reference to the precautionary principle is the 1985 Vienna Convention on Ozone Depleting Substances wherein parties agree to take "precautionary measures."⁵ It was first given specifics for implementation in the Ministerial Declaration of the Second International Conference on the Protection of the North Sea issued in London in November 1987.⁶ Canada successfully "advocated inclusion of the precautionary principle" during the Bergen Conference negotiations in 1990.⁷ In the late 1980s and early 1990s, while the principle was being endorsed in international agreements,⁸ seeds of precaution were also being planted in Canadian judicial decisions.