The increasing preparedness of Australian environmental managers to rely on the precautionary principle when exercising their legislative powers is testament to the principle's usefulness regarding a range of environmental management challenges. However, Australian legislation provides limited support for precautionary decision making because it adopts a vague formulation of the principle and appears to limit its application to circumstances when there are 'threats of serious or irreversible environmental damage'. Further, many environmental management agencies remain without express legislative instructions either to consider or apply the principle. The combination of a weak legislative mandate for precautionary decision making, and its potentially significant economic consequences for affected individuals, raises the prospect of a new wave of judicial review challenges against decisions which are arguably impermissibly precautionary. Such legal challenges to decisions made by environmental and planning agencies may not only result in their invalidation; they may also shape administrative culture in using the principle. This makes it necessary for care to be taken in how the principle is incorporated into rules and regulations so that decisions of government departments and agencies can be made in a manner consistent with the philosophy behind it. The Australian experience reveals that the legislative formulation of the principle may be pivotal in determining the lawfulness of precautionary management decisions. This experience is informative for other jurisdictions which·embed the principle in legislation.