The precautionary principle became internationally recognised at the United Nations Conference on Environment and Development, held in Rio de Janeiro in 1992.

Principle 15 of the Rio Declaration on Environment and Development described the principle as:

Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.

The Rio Declaration suggests that the principle should apply within three limits.

1. There must be threat of serious or irreversible damage. The principle is not restricted to current or certain future damage. There only needs to be a threat of damage. However, the anticipated damage must be serious or irreversible for the principle to apply.
   • Clearly, whether the threat is serious or irreversible is prone to disagreement, particularly when there is scientific uncertainty. At the least, there must be a scientific basis for the damage – ‘mere fantasy or crude speculation is not enough’. For further discussion on this see World Commission on the Ethics of Scientific and Technology paper on The Precautionary Principle
2. There must be scientific uncertainty. The precautionary principle applies where there is a ‘lack of full scientific certainty’ – that is, when science cannot say what consequences to expect, how grave they are, or how likely they are to occur.
3. Preventative measures must be proportionate. In the Rio Declaration, it is cost-effective measures that should not be postponed. Seemingly, threats that would be expensive to prevent may be risked. Cost-effectiveness is a question of proportionality – is the cost of preventing the damage proportional to the cost of dealing with damage that might eventuate? This balance is difficult to strike when there is scientific uncertainty.
   • See ‘Environmental Regulatory Decision-Making Under Uncertainty’ (p. 6) for four main ways to approach this balance.

In 1992, the Commonwealth government, all State and Territory governments, and the Australian Local Government Association agreed to the Intergovernmental Agreement on the Environment. Section 3.5 of the Agreement states that the precautionary principle should inform government decision-making processes.

This formulation is similar to the Rio Declaration, except that it replaces ‘cost-effective’ with ‘practicable’:

Where there are threats of serious or irreversible environmental damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation. In the application of the precautionary principle, public and private decisions should be guided by:

i. careful evaluation to avoid, wherever practicable, serious or irreversible damage to the environment; and

ii. an assessment of the risk-weighted consequences of various options.

Despite this agreement, the precautionary principle has not yet been adequately incorporated into State and Commonwealth legislation. A number of key environmental and land use Acts do not mention the principle, and many that do, do not incorporate it fully.

The Environment Protection and Biodiversity Conservation Act 1999 (Cth) sets out five ‘principles of ecologically sustainable development’, among which is the precautionary principle (section 3A).

Section 391 obligates the Environment Minister to consider the precautionary principle when making certain decisions (but not all decisions) under the Act. Generally, the relevant decisions relate to the approval of development plans or to environment management plans.

State legislation also includes the precautionary principle. In Victoria, section 1C of the Environment Protection Act 1970(Vic) reproduces the principle in the Intergovernmental Agreement on the Environment.

Surprisingly the Planning and Environment Act 1987 does not include the precautionary principle at all (or indeed the principle of ecologically sustainable development).

The following table lists Victorian Acts that use the precautionary principle

In Australia, the precautionary principle has received most attention in the NSW case Telstra Corporation Limited v Hornsby Shire Council in the NSW Land and Environment Court which concerned potential health impacts from a telephone signal tower. In that case, Chief Justice Preston considered the precautionary principle at length.

Earlier cases had also applied the precautionary principle. In Leatch v Director-General of National Parks and Wildlife Service (1993) 81 LGERA 270]] Shoalhaven City Council was planning to build a new road. It applied for a licence to take or kill endangered fauna in the building process. The Director-General granted the licence under the National Parks and Wildlife Act 1974 (NSW). Ms Leatch, a concerned citizen, contested the licence. Stein J held that the precise impact on endangered fauna was unknown, but may result in extinction. His Honour refused the licence by applying the precautionary principle. While there was no explicit provision for the precautionary principle in the Act, his Honour held that the principle was relevant to the subject matter, scope and purpose of the Act.

In Nicholls v Director-General of National Parks and Wildlife Service (1994) 84 LGERA 397]] Talbot J noted the limitations of applying the precautionary principle in law. He stated that ‘while it may be framed appropriately for the purpose of a political aspiration, its implementation as a legal standard could have the potential to create interminable forensic argument. Taken literally in practice it might prove to be unworkable.’ His Honour held that there was sufficient evidence before the Court in that case to make an informed decision, despite some factual uncertainty.

The precautionary principle is not specifically mentioned in the Planning and Environment Act 1987 however it is relevant to planning decisions through indirect references in the State Planning Policy Framework clause 11.03-2. In light of this, the precautionary principle has been applied inconsistently in VCAT.

In some cases, such as Gippsland Coastal Board VCAT can be seen to be trying to introduce some clarity about how pressing planning issues such as sea level rise should be addressed by drawing on the precautionary principle. In other cases, however, an erroneous approach has been taken. In Western Water v Rozen & Anor [2008] VSC 382, the Supreme Court overturned the decision of VCAT in Rozen v Macedon Ranges SC (Red Dot) [2007] VCAT 1814. The Supreme Court held that the Tribunal had misunderstood the scope and operation of the precautionary principle, at least as the principle was included in the relevant State Environment Protection Policy. The Supreme Court direct VCAT to rehear the matter applying the precautionary principle correctly. The resulting decision, Rozen v Macedon Ranges SC (Red Dot) [2009] VCAT 2746, suggests that VCAT is more towards a consistent and relatively rigorous application of the precautionary principle.

The first time the precautionary principle has been specifically incorporated into the planning framework in Victoria is through the recent Victorian Planning Provisions amendment regarding coastal impacts in clause 15.08.

• Environment Protection Act 1970 (Vic)

• Myers v South Gippsland SC (Red Dot) [2009] VCAT 1022 (22 June 2009)

• Fisheries Management Act 1991 (Cth)

• Likely to have a significant impact on a matter of National Environmental Significance

• Ecologically Sustainable Development and the Planning and Environment Act 1987

• Section 391 of the Environment Protection and Biodiversity Conservation Act 1999

• Precautionary_principle

• Telstra Corporation Limited v Hornsby Shire Council, NSW Land and Environment Court

• Rio Declaration on Environment and Development