This chapter examines the nature of fiduciary duties in Australia and the direction the High Court of Australia has been taking in relation to fiduciary theory. It focuses on whether climate change fiduciary duties are possible under Australian general law. The chapter reviews the types of fiduciary duties that could be recognised in light of the High Court's more recent statements on the fiduciary principle. The fiduciary principle has not traditionally been limited to the conflicts and profits rules. For example, company directors have for many years been subject to additional fiduciary duties. A number of commentators and judges have expressed the view that Australian fiduciary duties are now limited to the conflicts and profits rules. The use of the fiduciary model to impose positive duties to protect the environment and prevent climate change is likely to be difficult in Australia due to the High Court's recent statements on fiduciary theory.