Justice Preston is the Chief Judge of the Land and Environment Court in New South Wales. Prior to being appointed in November 2005, he was a senior counsel practising primarily in New South Wales in environmental, planning, administrative and property law.

He holds a Bachelor of Arts and a Bachelor of Laws (1st Class Honours) from Macquarie University, practised as a solicitor from 1982-1987, and then at the bar from 1987-2005. He was appointed senior counsel in 1999.

He has lectured in post-graduate, environmental law for over 23 years, principally at the University of Sydney, but also at other universities in Australia and overseas. He established two law courses: environmental dispute resolution and biodiversity law. He is currently an Adjunct Professor at the University of Sydney.

Justice Preston is the author of Australia's first book on environmental litigation (in 1989) and over 90 articles, book chapters and reviews on environmental law, administrative and criminal law. The subjects of his writings include: the law and the environment; sustainable development; biodiversity; climate change; heritage; environmental impact assessment; environmental crime; the courts and the environment; public interest litigation; and administrative law and environmental law.

He holds editorial positions for environmental law publications, including General Editor of the Local Government Planning and Environment NSW Service and Title Editor for the Laws of Australia, Title 14 - Environment and Natural Resources, and is a member of the editorial advisory boards of the Asia Pacific Journal of Environmental Law and Legal Perspectives on Global Challenges, Eleven International Publishing.

He has been involved in a number of international environmental consultancies and capacity-building programs, including for the judiciaries in Indonesia, Kenya, China, Trinidad and Tobago, Thailand and Sri Lanka.

Justice Preston is an Official Member of the Judicial Commission of NSW; Chair of the Environmental Law Standing Committee of the Law Association for Asia and the Pacific; member of the Environmental Law Commission of the International Union for Conservation of Nature; member of the Australian Centre for Climate and Environmental Law; member of the Advisory Committee of the Asia Pacific Centre for Environmental Law (National University of Singapore); member of the Adhoc Advisory Committee of Judges, United Nations Environment Programme Judges Program; member of the Advisory Group on the Guide to the UNEP Bali Guidelines on Rio Principle 10; and member of the International Bar Association President's Climate Change Justice and Human Rights Task Force. He has been inducted as a Fellow of the Australian Academy of Law.

He is the recipient of a Commendation in the 2010 Australasian Institute of Judicial Administration, Award for Excellence in Court Administration, for his work in implementing the International Framework for Court Excellence in the Land and Environment Court of New South Wales. He is also the recipient in 2010 of an award by the Asian Environmental Compliance and Enforcement Network in recognition of his outstanding leadership and commitment in promoting effective environmental adjudication in Asia.

Justice Preston has provided significant support to the EIANZ, its members and the broader profession specialising in environmental law in NSW. He facilitated the participation of the Land and Environment Court, and the broader legal profession, in the EIANZ's expert witness training courses. As part of this, he served as a keynote presenter at these courses.

Justice Preston was awarded Honorary Fellowship membership of the Environment Institute of Australia and New Zealand in 2014.