3. The principle of the precautionary approach to human health, natural resources and ecosystems

The history of the industrial world is often characterized by innovation and progress. But sometimes discoveries, practices and inventions turn out to have dangerous consequences. Examples such as asbestos, ozone depleting compounds, chemical pollution and burning fossil fuels show the dangers can be to our health or to our environment, and that harmful effects can be immediate or delayed, local or global. Unfortunately, in many cases, activities that are suspected - and even known - to cause serious damage may continue despite evidence of the harm they cause. This is why it is essential for governments and businesses to use the precautionary principle. It is a way to ensure that where there are threats of serious or irreversible harm, action is taken quickly. 


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 degradation. The burden of proof shifts to those proposing activities which might cause serious harm. In order to protect the environment, natural resources and human health, the precautionary principle shall be widely applied by law and policy makers, according to their capabilities. It favours prevention over remediation, focuses on the relevance and robustness of scientific data to development decision-making and carries an obligation to use precautionary measures in proportion to potential damage and the likelihood or degree of risk involved in each case.

Download CISDL draft legal working paper on the precautionary principle

Download CISDL legal working paper on the 7 Future Justice principles


This principle is already widely recognized in international law or practice. For example:

Convention on Biological Diversity

“Noting that it is vital to anticipate, prevent and attack the causes of significant reduction or loss of biological diversity at source,
Noting also that where there is a threat of significant reduction or loss of biological diversity, lack of full scientific certainty should not be used as a reason for postponing measures to avoid or minimize such a threat,…”

Preamble, UN Convention on Biological Diversity, 1992


Cartagena Protocol

“In accordance with the precautionary approach contained in Principle 15 of the Rio Declaration on Environment and Development, the objective of this Protocol is to contribute to ensuring an adequate level of protection in the field of the safe transfer, handling and use of living modified organisms resulting from modern biotechnology that may have adverse effects on the conservation and sustainable use of biological diversity, taking also into account risks to human health, and specifically focusing on transboundary movements.”

Article 1, The Cartagena Protocol on Biosafety, 2000

Convention on Climate Change

"In their actions to achieve the objective of the Convention and to implement its provisions, the Parties shall be guided, inter alia, by the following:…
3. The Parties should take precautionary measures to anticipate, prevent or minimize the causes of climate change and mitigate its adverse effects. Where there are threats of serious or irreversible damage, lack of full scientific certainty should not be used as a reason for postponing such measures, taking into account that policies and measures to deal with climate change should be cost-effective so as to ensure global benefits at the lowest possible cost. To achieve this, such policies and measures should take into account different socio-economic contexts, be comprehensive, cover all relevant sources, sinks and reservoirs of greenhouse gases and adaptation, and comprise all economic sectors. Efforts to address climate change may be carried out cooperatively by interested Parties."

Article 3.3, UN Convention on Climate Change, 1992

Stockholm POPs Convention

“Mindful of the precautionary approach as set forth in Principle 15 of the Rio Declaration on Environment and Development, the objective of this Convention is to protect human health and the environment from persistent organic pollutants…..

9. The Conference of the Parties, taking due account of the recommendations of the Committee, including any scientific uncertainty, shall decide, in a precautionary manner, whether to list the chemical, and specify its related control measures, in Annexes A, B and/or

Articles 1 and 8.9,  Stockholm Convention on Persistent Organic Pollutants, 2001

Straddling Fish Stocks Agreement

“1. States shall apply the precautionary approach widely to conservation, management and exploitation of straddling fish stocks and highly migratory fish stocks in order to protect the living marine resources and preserve the marine environment.

2. States shall be more cautious when information is uncertain, unreliable or inadequate. The absence of adequate scientific information shall not be used as a reason for postponing or failing to take conservation and management measures.”

Article 6.1 and 6.2, the Agreement for the Implementation of the Provisions of the U.N. Convention on the Law of the Sea of 10 December 1982 relating to the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks, 1995

WTO Agreement

“1.        Members shall ensure that their sanitary or phytosanitary measures are based on an assessment, as appropriate to the circumstances, of the risks to human, animal or plant life or health, taking into account risk assessment techniques developed by the relevant international organizations…

7.        In cases where relevant scientific evidence is insufficient, a Member may provisionally adopt sanitary or phytosanitary measures on the basis of available pertinent information, including that from the relevant international organizations as well as from sanitary or phytosanitary measures applied by other Members.  In such circumstances, Members shall seek to obtain the additional information necessary for a more objective assessment of risk and review the sanitary or phytosanitary measure accordingly within a reasonable period of time.”

Article 5.1 and 5.7, Agreement on the Application of Sanitary and Phytosanitary Measures, 1994

“…the precautionary principle indeed finds reflection in Article 5.7 of the SPS Agreement. We agree, at the same time, with the European Communities, that there is no need to assume that Article 5.7 exhausts the relevance of a precautionary principle…[T]he Appellate Body…upholds the Panel's conclusions that the precautionary principle…has been incorporated in, inter alia, Article 5.7 of the SPS Agreement;.”
Measures Concerning Meat and Meat Products (Hormones) (Compliance USA and Canada) (13 February 1998), WTO Doc WT/DS26/AB/R, WT/DS48/AB/R (Appellate Body Report), Parts VI and XIV

Questions and resources

The 3 questions below can be used to focus upon this principle, and to test the action of any law or policy:

3.1 Does the law/policy promote prevention and precaution in the face of scientific uncertainty about a threat of serious or irreversible harm?

3.2 Does it place the burden of proof for demonstrating that a project or activity is safe, or that risks are reasonable, on the proponent of the venture?

3.3 Where there is insufficient scientific evidence, does it ensure that those most affected by a project can set the acceptable level of risk or threat?

The links below have been selected because we think they contain information which may help policy-makers develop laws and policies in the context of this principle and these questions: 

  • This 2005 overview report - from UNESCO’s advisers, the World Commission on the Ethics of Scientific Knowledge and Technology - provides an excellent synopsis of the precautionary principle and aims to offer “an ethical platform to ensure proper risk management and correct information to the public and to policy makers”. 
  • This 2001 report  by the European Environment Agency draws out 12 lessons for future decision-making from the decisions made relating to occupational, public and environmental hazards associated with 14 economic activities during the 20th century: namely, fisheries, radiation, benzene, asbestos, PCBs, halocarbons, diethylstilboestrol (DES), antimicrobials as growth promoters, sulphur dioxide, MTBE as lead substitute in petrol, chemical contamination of the Great Lakes, tributyltin antifoulants, hormones as growth promoters, and mad cow disease.


This report covers case studies of particular relevance to Europe and North America, written by respected issue experts. They were asked to structure their report around 4 key questions: when was the first credible scientific ‘early warning’ of potential harm? When and what were the main actions or inactions on risk reduction taken by regulatory authorities and others? What were the resulting costs and benefits of the actions or inactions, including their distribution between groups and across time? What lessons can be drawn that may help future decision-making?

12 lessons were identified:

  • respond to ignorance as well as uncertainty
  • research and monitor for ‘early warnings’
  • search out and address ‘blind spots’ and gaps in scientific knowledge 
  • identify and reduce interdisciplinary obstacles to learning
  • ensure that real world conditions are fully accounted for
  • systematically scrutinize and justify the claimed ‘pros’ and ‘cons’
  • evaluate alternatives and promote robust, diverse and adaptable solutions
  • use ‘lay’ and local knowledge as well as all relevant specialist expertise; take account of wider social interests and values
  • maintain regulatory independence from economic and political special interests
  • identify and reduce institutional obstacles to learning and action
  • and  avoid paralysis by analysis.

Download ‘Late lessons from early warnings: the precautionary principle 1896-2000’ (Environmental issue report No. 22) here.

  • The European Commission’s guidelines for applying the precautionary principle are set out in this document.
  • The IUCN-approved Guidelines for Applying the Precautionary Principle to Biodiversity Conservation and Natural Resource Management are here.
  • The 2008 International Guidelines for the Management of Deep-Sea Fisheries in the High Seas provide guidance in section 5.4 on precautionary conservation and management measures to protect against bottom trawling. These include catch and effort controls, stock reviews and closure of deep sea fisheries.