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Environmental law regularly operates in areas complicated by high levels of scientific uncertainty. In the case of many activities that entail some change to the environment, it is impossible to determine precisely what effects the activity will have on the quality of the environment or on human health. Often available scientific evidence provides us cause for concern but does not give conclusive information. In such scenarios risk assessment compels us to strike a balance between the need to protect health and environment on one hand, and the foregone advantages of strict restrictions that may turn out to be unwarranted. It is in this context the role for Precautionary Principle emerges. While deciding the need and timing of the application of the Precautionary Principle, it is important to clearly understand the principle and its consequences.

The Precautionary Principle is one of the most contentious principles in contemporary International legal developments. The very fact that is, a principle of international environmental law has been questioned by many legal scholars. However, this does not take away the fact that the Precautionary Principle continues to be applied widely across sectors both internationally and nationally. The nature and scope of its application has varied widely according to the context and sector within which it has been applied.

Precautionary Principle’ plays a significant role in determining whether developmental process is sustainable or not. ‘Precautionary Principle’ underlies sustainable development which requires that the developmental activity must be stopped and prevented if it causes serious and irreversible environmental damage. The emergence of Precautionary Principle marks a shift in the international environmental jurisprudence- a shift from assimilative capacity principle to Precautionary Principle.


The Precautionary Principle is a tool for making better health and environmental decisions. It aims to prevent harm from the outset rather than manage it after the fact. In common language, this means “better safe than sorry.” The Precautionary Principle denotes a duty to prevent harm, when it is within our power to do so, even when all the evidence is not in.[1] In short, the “precautionary principle” is a notion which supports taking protective action before there is complete scientific proof of a risk; that is, action should not be delayed simply because full scientific information is lacking.[2]

In simple terms, the Precautionary Principle conveys the common-sense based advice to err on the side of caution. The principle intends to prevent harm to humans, environment, and eco-system at large. Before looking at some of the widely used definitions of the Precautionary Principle, it would be helpful to understand the context and rationale. When the impacts of a particular activity – such as emission of hazardous substances – are not completely clear, the general presumption is to let the activities go ahead until the uncertainty is resolved completely. The Precautionary Principle counters such general presumptions. When there is uncertainty regarding the impacts of an activity, the Precautionary Principle advocates action to anticipate and avert environmental harm. Thus, the Precautionary Principle favors monitoring, preventing and/or mitigating uncertain potential threats.

There are two widely referred definitions of the Precautionary Principle. One of the most important expressions of the Precautionary Principle internationally is in the Rio Declaration from the 1992 United Nations Conference on Environment and Development, also known as Agenda 21. The declaration stated: ‘In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. 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 second definition is based on 1998 Wingspread Statement on the Precautionary Principle and it states: “...When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. The process of applying the precautionary principle must be open, informed and democratic and must include potentially affected parties. It must also involve an examination of the full range of alternatives, including no action. In this context the proponent of an activity, rather than the public, should bear the burden of proof.

Precautionary Principle’ plays a significant role in determining whether developmental process is sustainable or not. ‘Precautionary principle’ underlies sustainable development which requires that the developmental activity must be stopped and prevented if it causes serious and irreversible environmental damage. The emergence of Precautionary Principle marks a shift in the international environmental jurisprudence- a shift from assimilative capacity principle to Precautionary Principle.

Assimilative Capacity Principle: Assimilative capacity principle underlies earlier legal measures to protect the environment. Before the Stockholm Conference 1972, the concept of ‘Assimilative Capacity’ was recognized at the international level. As per this concept the natural environment has the capacity to absorb the ill-effects of the pollution but beyond a certain limit the pollution may cause damage to the environment requiring efforts to repair it. Principles 6 of the Stockholm Declaration contains assimilative capacity principle which assumes that science could provide the policy makers with the necessary information and means to avoid encroaching upon the capacity of the environment to assimilate impacts and it presumes that relevant technical expertise would be available when environmental harm is predicted and there would be sufficient time to act in order to avoid such harm.

Assimilative Capacity to Precautionary Principle – A Shift: The uncertainty of scientific proof and its changing frontiers from time to time have led to great changes in the environmental concepts during the period between the Stockholm Conference of 1972 and the Rio Conference of 1992. A basic shift to the approach to environmental protection occurred initially between 1972 and 1982. Earlier the concept was based on the assimilative capacity rule as revealed from principle 6 of the Stockholm Declaration. So, Precautionary Principle is a principle which ensures that a substance or activity posing a threat to the environment is prevented from adversely affecting it, even if there is no conclusive scientific proof lining that particular substance or activity to the environmental damage. The words ‘substance’ and ‘activity’ imply substance or activity introduced as a result of human intervention.


The Precautionary Principle is a narrower concept than merely looking for safety. Precautionary ‘thinking’ has a much longer history. The Late Lessons from Early Warnings report (2001) mentions the example of Dr. John Snow who in 1854 recommended removing the handle of a London water pump in order to stop a cholera epidemic. The evidence for the causal link between the spread of cholera and contact with the water pump was weak and not a proof beyond reasonable doubt. The report then mentions a series of other examples, such as asbestos, where a precautionary approach could have saved many lives if early warnings of potential at the time unproven but still reducible harm had been taken more seriously.[3]

The Precautionary Principle, however, dates from the 1970s. Some scholars mention a Swedish and some a German origin of the Precautionary Principle. The term ‘Precautionary Principle’ had its origin in the German word Vorsorgeprinzip[4]. In Germany the Precautionary Principle (‘Vorsorgeprinzip’) may be traced back to the first draft of a bill (1970) aimed at securing clean air. The law was passed in 1974 and covered all potential sources of air pollution, noise, vibrations and similar processes. The most unambiguous elaboration of the Precautionary Principle in German environmental policy is from a later date and reads: ‘Responsibility towards future generations commands that the natural foundations of life are preserved and that irreversible types of damage, such as the decline of forests, must be avoided.’ Thus the principle of precaution commands that the damages done to the natural world (which surrounds us all) should be avoided in advance and in accordance with opportunity and possibility.


Five Key Elements of the Precautionary Principle:
The Precautionary Principle represents a paradigm shift in decision-making. It allows for five
key elements that can prevent irreversible damage to people and nature[5]:
  1. Anticipatory Action: There is a duty to take anticipatory action to prevent harm. Government, business, and community groups, as well as the general public, share this responsibility.
  2. Right to Know: The community has a right to know complete and accurate information on potential human health and environmental impacts associated with the selection of products, services, operations, or plans. The burden to supply this information lies with the proponent, not with the general public.
  3. Alternatives Assessment: An obligation exists to examine a full range of alternatives and select the alternative with the least potential impact on human health and the environment, including the alternative of doing nothing.
  4. Full Cost Accounting: When evaluating potential alternatives, there is a duty to consider all the reasonably foreseeable costs, including raw materials, manufacturing, transportation, use, cleanup, eventual disposal, and health costs even if such costs are not reflected in the initial price. Short and long-term benefits and time thresholds should be considered when making decisions.
  5. Participatory Decision Process: Decisions applying the Precautionary Principle must be transparent, participatory, and informed by the best available science and other relevant information.


The effects of careless and harmful activities have accumulated over the years. Humans and the rest of the natural world have a limited capacity to absorb and overcome this harm. There are plenty of warning signs:
·         Chronic diseases and conditions affect more than 100 million men, women, and children in the World—more than a third of the population. Cancer, asthma, Alzheimer's disease, autism, birth defects, developmental disabilities, diabetes, endometriosis, infertility, multiple sclerosis, and Parkinson's disease are becoming increasingly common.
·    In laboratory animals, wildlife, and humans, considerable evidence documents a link between levels of environmental contamination and malignancies, birth defects, reproductive problems, impaired behavior, and impaired immune system function. Scientists' growing understanding of how biological systems develop and function leads to similar conclusions.
·        Other warning signs are the dying off of plant and animal species, the destruction of ecosystems, the depletion of stratospheric ozone, and the likelihood of global warming.
Serious, evident effects such as endocrine disruption, climate change, cancer, and the disappearance of species can seldom be linked decisively to a single cause. Scientific standards of certainty may be impossible to attain when causes and outcomes are multiple; latent periods are long; timing of exposure is crucial; unexposed, “control” populations do not exist; or confounding factors are unidentified.


Several multilateral environmental agreements refer to precautionary principle in some form, but rarely provide elaboration into specific guidance. Similarly, several national level environmental initiatives invoke the precautionary principle. Here, a brief overview of some such initiatives is provided.


a)   Montreal Protocol on Substances that Deplete the Ozone Layer, 1987 – ‘Parties to this Protocol, determined to protect the ozone layer by taking precautionary measures to control equitably total global emissions of substances that deplete it..’

b)    The Rio Declaration on Environment and Development, 1992 – ‘In order to protect the environment the precautionary approach shall be widely applied by states according to their capabilities.’

c)  UN Framework Convention on Climate Change, 1992 – Article 3.3 says, “The Parties should take precautionary measures to anticipate, prevent or minimize the causes of climate change and mitigate its adverse effects.”

d)     Convention on Biological Diversity, 1992 – This Convention does not directly use the term ‘precaution’ but interprets the ‘serious and irreversible’ harm referred in the Rio Declaration in the context of biodiversity. It states,  “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.”

e)      The Maastricht Treaty of European Union, 1992 – “Community policy on the environment must aim at a high level of protection and be based on the precautionary principle, as well as on the principle that preventive action should be taken, that environmental damage should be rectified at source and that the polluter should pay.

f)      Cartagena Protocol on Bio-safety, 2000 – “In accordance with the precautionary approach 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 into account risks to human health, and specifically focusing on trans-boundary movements.”

g)     Stockholm Convention on Persistent Organic Pollutants (POPs), 2001 – The objective states, “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 environment from persistent organic pollutants.” This treaty operationalizes precaution with explicit reference to it in the preamble, provisions for adding POPs, and determination of best available technologies.


a)    Asia – Even though several countries have adopted well drafted environmental and biodiversity laws, reference to ‘precautionary principle’ is missing. For instance, Malaysia’s National Biodiversity Policy makes explicit reference to the Convention on Biological Diversity (1992) but refrains from using the term ‘precautionary principle’. Similarly other countries in the region, Vietnam, Indonesia and Lao PDR also do not directly invoke precautionary principle in their laws. On the other hand, in several countries (e.g., India and Pakistan) the highest judicial authority has cited ‘precautionary principle’ in its judgments.

b)    Africa – Several countries have made explicit reference to ‘precautionary principle’ in their laws. Examples include the 1997 Mozambique Environment Legislation, the 1996 General Environmental Law of Cameroon, and South Africa’s National Environmental Management Act.

c)  Latin America – Many countries in this region have incorporated precaution as guiding principle in their national environmental laws. Examples include general and biodiversity related environmental laws in Argentina, Peru, Costa Rica and Ecuador.

d)   Australia – The precautionary principle is deeply rooted in Australia’s environmental policy, as reflected in the Inter-Governmental Agreement on Environment of 1992, and the Commonwealth Environment Protection and Biodiversity Conservation Act of 1999.

As mentioned above, precaution is deeply entrenched in the environmental legislations of several European countries. On the other hand, in the United States of America precaution is rarely stated explicitly in any of its laws. However, the precautionary the principles are well entrenched in several protection acts such as Endangered Species Act of 1973, and the Wild Bird Conservation Act of 1992.


In India, there are lots of environmental regulations but environmental regulations as Water (Prevention and Control of Pollution) Act, 1974, the Air (Prevention and Control of Pollution) Act, 1981, and the Environment (Protection) Act, 1986 are aimed at cleaning up pollution and controlling the amount of it released into the environment. They regulate the harmful substances as they are emitted rather than limiting their use or production in the first place. These laws are based on the assumption that humans and ecosystem can absorb a certain amount of contamination without being harmed. But the past experience shows that it is very difficult to know what levels of contamination, if any, are safe and therefore, it is better to err on the side of caution while dealing with the environment.[7]

The Precautionary Principle has not been explicitly mentioned in any environmental laws in India. However, the Supreme Court of India has invoked this principle while passing judgments.
Building on some of the near-precautionary approaches we saw in Indian legislation, in Punjab v. Modern Cultivators, Ladwa[8], and Rajkot Municipal Corporation v. Manjulben Jayantilal Nakum[9], expectations for precaution are used as measures of tort liability. The Oleum Gas Leak Case[10] extends the principle of strict and absolute liability for those engaged in hazardous activities, thus providing the necessary impetus for precautionary action when dealing with toxic materials and allowing punishment for a failure to err on the side of caution.

Precautionary Principle does not find any place in judicial decisions in India before Vellore Citizens Welfare Forum v. Union of India[11], where Supreme Court referred the Brundtland Report and other international documents in addition to Articles 21, 48A and 51A(g) of the Constitution of India. And also taken into account the legislative mandate “to protect and improve the environment” as found in enactments like the Water (Prevention and Control of Pollution) Act, 1974, the Air (Prevention and Control of Pollution) Act, 1981, and the Environment (Protection) Act, 1986.

Drawing support from various Articles of the Constitution of India and arguing that the Precautionary Principle is part of customary international laws (and hence part of domestic laws), the Court has strongly supported the application of precautionary principle. In fact, the Court has also applied the reversal of burden of proof and demanded that the proponents of the activity must demonstrate that the activity is environmentally benign. In this case the Court explained the meaning of ‘Precautionary Principle’ in the context of municipal law as under[12]:
        i.         Environmental measures by the State Government and the Statutory Authorities – must anticipate, prevent and attack the causes of environmental degradation.
      ii.            Where there are threats of serious and irreversible damage, lack of scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation.
    iii.        The onus of proof is on the actor or the developer/industrialist to show that his action is environmentally benign.

In Taj Trapezium Case[13] the Supreme Court was dealing with the problem of protecting the ‘Taj Mahal’ from the pollution of nearby industries. The Court applied the ‘Precautionary Principle’ as explained by it in Vellore case and observed – The environmental measures must anticipate, prevent and attack the causes of environmental degradation. The ‘onus of proof’ is on an industry to show that its operation with the aid of coke/coal is environmentally benign. It is rather, proved beyond doubt that the emissions generated by the use of coke/coal by the industries in Taj Trapezium are the main polluters of the ambient air.
The court ordered the industries to change over to the natural gas as an industrial-fuel or stop functioning with the aid of coke/coal in the Taj trapezium and relocate themselves as per the directions of the Court.

In Calcutta Tanneries Case[14] applying the Precautionary Principle Court ordered the polluting tanneries operating in the city of Calcutta (about 550 in numbers) to relocate themselves from their present location and shift to the new leather complex set-up by the West Bengal Government.

In Badkhal & Surajkund Lakes Case[15] the Supreme Court held that the ‘Precautionary Principle’ made it mandatory for the State Government to anticipate, prevent and attack the causes of environmental degradation. The Court has no hesitation in holding that in order to protect the two lakes from environmental degradation it was necessary to limit the construction activity in the close vicinity of the lakes.

Even though the Vellore judgment was followed in the subsequent decisions of the Supreme Court, the Court felt the need to explain the meaning of the ‘Precautionary Principle’ in more detail and lucid manner so that Courts & Tribunals or Environmental Authorities can properly apply the said principle in the matters which might come before them. In A P Pollution Control Board v. Prof. M. V. Nayudu[16] the Supreme Court has reiterated its earlier stand on the precautionary principle and demanded that the burden of proof should rest with the person/entity proposing the activities (which may have harmful effects on the environment and/or human beings).

In Narmada Bachao Andolan v. Union of India[17], precautionary principle came to be considered by the majority of judges. The Court also took the view that the doctrine is to be employed only in cases of pollution when its impact is uncertain and non-negligible.

In S. Jagannath v. Union of India[18], the Supreme Court held that sea beaches and sea coasts are gifts of nature and any activity polluting the same cannot be permitted. The intensified shrimp (prawn) farming culture industry by modern method in coastal areas was causing degradation of mangrove ecosystem, depletion of plantation discharge of highly polluting effluents and pollution of potable as well as ground water.

In KM Chinnappa, TN Godavarman Thirumalpad v. Union of India[19], the Court recognized the importance of India’s treaty obligations, placing the precautionary principle in this case in the context of the Convention on Biological Diversity. Despite India’s dualist legal tendencies and a lack of implementing legislation at the time, the government was held responsible for adhering to its treaty responsibilities that did not conflict with domestic statutes. In this case, mining in the Kudremukh National Park was deemed to be inconsistent with the precautionary nature of India’s treaty requirements.

Despite these newly strengthened precautionary statements, the principle has not achieved complete success in the Indian legal system. In particular, precaution has been waived in cases of dam building proposals. In 1992, the Tehri dam case suggested that a standard of “quite safe” was sufficient despite the tremendous potential damage likely if the dam broke. The Court seems to have moved on very little since then, declining to apply precaution because the case is not about a “polluting industry.” The Court suggests that the precautionary principle is only applicable where the science is uncertain and damages cannot be calculated. Somehow, it determines that the future impacts of dam construction on the Narmada River are clear, requiring mitigation to balance the harm rather than advance precaution. In addition to these judicial limitations on the precautionary principle, some commentators suggest that the courts’ environmentalism is somewhat irrelevant in light of enforcement difficulties.[20]


The Precautionary Principle is relatable to risk assessment and environmental impact assessment. Broadly, it postulates that decisions that may have an impact on the environment need to allow for and recognize conditions of uncertainty, particularly with respect to the possible environmental consequences of those decisions. Under the circumstances, it is essential to take preventive action or avoid effects, which may be damaging even if this cannot be proven. In short, the “Precautionary Principle” is a notion which supports taking protective action before there is complete scientific proof of a risk; that is, action should not be delayed simply because full scientific information is lacking.

The precautionary principle has been viewed as an important element of environmental policy since the Rio Declaration of 1992 and is widely believed to be favorable to the conservation of existing natural environments and the current stock of biodiversity including measures to avoid deterioration in these. Previously Precautionary Principle is being used only on the matter of the Environmental pollution but today this is being used to deal with the wild life protection, Biodiversity Conservation, matters related to climate change, protection of shrimps etc.

[4] Interestingly, an alternative translation of this word would mean ‘foresight principle’ – which could have given an active and positive impression, as against the reactive and perhaps negative connotation attached with precaution.
[6] K. S. Kavi Kumar, Precautionary Principle, Dissemination Paper, Centre of Excellence in Environmental Economics.
[7] Tiwari A. K, Environmental Laws in India, 2006, Deep and Deep Publications Pvt. Ltd. New Delhi. p. 216
[8] 1964 SCR (8) 273
[9] (1997) 9 SCC 552
[10] M. C. Mehta v. Union of India, Writ Petition (Civil) No.12739 of 1985
[11] Vellore Citizens Welfare Forum v. Union of India, AIR 1996 SC 2715
[12] Tiwari A. K, Environmental Laws in India, 2006, Deep and Deep Publications Pvt. Ltd. New Delhi. p. 217
[13] AIR 2002 SC 3696
[14] (1997) 2 SCC 411
[15] M. C. Mehta (Suraj Kund & Badkhal Lakes matter) v. Union of India (1997) 3 SCC 715
[16] [1999] 2 SCC 718
[17] 2005(4 ) SCC 32
[18] (1997) 2 SCC 87
[19] 2002 (10) SCC 606


  1. thanks!! this info helped me

  2. This is a nice ready reckoner. Might I suggest formatting the endnotes?

  3. Nice blog and very informative thank you for sharing such a great blog.

  4. Really informative. Save my life.


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