Interdepartmental Liaison Group on Risk
The purpose of ILGRA is to help secure coherence
and consistency within and between policy and practice in risk
assessment as undertaken by Government, and help disseminate and
advance good practice. ILGRA reports to Ministers.
Ministers have agreed that this paper should
be published on the ILGRA website.
ILGRA welcomes comments on this paperplease
send your comments to the ILGRA Secretariat, email@example.com
by 30 September 2002.
This paper outlines policy guidelines on the
precautionary principle agreed by the Interdepartmental Liaison
Group on Risk Assessment (ILGRA). The key points are:
The purpose of the precautionary
principle is to create an impetus to take a decision notwithstanding
scientific uncertainty about the nature and extent of the risk.
Although there is no universally
accepted definition, the Government is committed to using the
precautionary principle, which is included in the 1992 Rio Declaration
on Environment and Development.
The precautionary principle should
be invoked when:
there is good reason to believe
that harmful effects may occur to human, animal or plant health
or to the environment; and
the level of scientific uncertainty
about the consequences or likelihood of the risk is such that
the best available scientific advice cannot assess the risk with
sufficient confidence to inform decision-making.
The precautionary principle should
be distinguished from other drivers that require caution such
as society's view on the extent of protection afforded to children
or others considered to be vulnerable, or the wish to ensure that
conventional risk assessment techniques deliberately over rather
than under-estimate risk.
Action in response to the precautionary
principle should accord with the principles of good regulation,
ie be proportionate, consistent, targeted, transparent and accountable.
Applying the precautionary principle
is essentially a matter of making assumptions about consequences
and likelihoods to establish credible scenarios, and then using
standard procedures of risk assessment and management to inform
decisions on how to address the hazard or threat.
Decision-making should bring together
all relevant social, political, economic, and ethical factors
in selecting an appropriate risk management option.
Invoking the precautionary principle
shifts the burden of proof in demonstrating presence of risk or
degree of safety towards the hazard creator. The presumption should
be that the hazard creator should provide, as a minimum, the information
needed for decision-making.
Decisions reached by invoking and
applying the precautionary principle should be actively reviewed,
and revisited when further information that reduces uncertainty
| Introductionneed for a consistent approach
| Definition of the precautionary principle
| Purpose of the precautionary principle
| Invoking the precautionary principle
| The precautionary principle and other cautionary policies
| Extent of precautiongood regulation
| Applying the precautionary principle
| Credible scenarios
| Openness and transparency
| Burden of proof
| Hierarchy of controls
| Annex 1Contrasting views on precaution
| Annex 2European Resolution on the precautionary principle
| Annex 3Credible Scenarios
Need for a consistent approach
1. Intuitively, precaution should be easythe proverbial
"better safe than sorry". However, for regulators precaution
is often controversial, with no simple answers.
2. Precaution is controversial because the "why",
"when" and "how" of precautionary intervention
goes to the heart of the regulation of hazardous activities and
their place in society. For example, a view that risks should
be managed and hazardous activities banned only as a last resort
would not be shared by those who favour risk avoidance and so
would prefer to remove the hazard altogether.
3. Annex 1 develops this into a spectrum of contrasting
views on the precautionary principle, ranging from "weak"
to "strong" precaution. In practice the position adopted
should reflect the commitment to sustainable development that
gives full weight to economic, social and environmental factors.
The precautionary principle should not, therefore, be an obstacle
to innovation. Properly applied it is a positive, proportionate
policy tool to encourage technological innovation and sustainable
development by helping to engender stakeholder confidence that
appropriate risk control measures are in place.
4. Although it is widely accepted that the precautionary
principle should be invoked in deciding how hazardous activities
should be addressed, there is considerable debate about what the
principle means, and about how it should be applied in practice.
There is an obvious need for consistency between Departments.
Ministers endorsed ILGRA's second report (December 1998) ,
which included a remit to "develop a consistent policy on
a precautionary approach". This initiative was picked up
in the commitment in the Sustainable Development White Paper 
(May 1999) "to develop a more consistent approach to the
principle across Government" and to "report on this
work in forthcoming reports on this Strategy". ILGRA's work
on the precautionary principle is also noted in the Government's
response to the Phillips Inquiry on BSE .
5. The policy proposed in the following paragraphs seeks
to clarify and develop existing understanding, and should underpin
domestic application of the precautionary principle by Departments.
The policy is broadly consistent with, but elaborates on, the
European Commission's Communication  on the precautionary principle,
which was broadly endorsed by EU Heads of Government in a European
Council Resolution at Nice in December 2000 . The main elements
of the Resolution are summarised in Annex 2. As with any policy,
however, its application is subject to constraints such as the
requirements of existing international treaties or agreements.
Nevertheless, the policy is intended to be forward-looking and
should inform the UK line in negotiating these treaties and agreements
as they evolve.
6. There is no universally accepted definition of the
precautionary principle. The Sustainable Development White Paper,
set out the Government's commitment to use the precautionary principle
by reference to the 1992 Rio Declaration on Environment and Development
"Where there are threats of serious or irreversible
environmental damage, lack of full scientific certainty shall
not be used as a reason for postponing cost effective measures
to prevent environmental degradation."
Since "Rio", however, the UK has signed a number
of international agreements which include different formulations
of the precautionary principle, reflecting the context and negotiating
7. Although the precautionary principle was originally
framed in the context of preventing environmental harm, it is
now widely accepted as applying broadly where there is threat
of harm to human, animal or plant health, as well as in situations
where there is a threat of environmental damage.
8. However, the definition is only a starting point.
Policy guidelines are needed to indicate when, for example, the
precautionary principle should be invoked, how a risk-based approach
can continue to be followed when the scientific uncertainty is
such that conventional risk assessment cannot in itself determine
the level of risk, and how decisions should be made on appropriate
9. The definition makes clear that where there is scientific
uncertainty the precautionary principle establishes an impetus
to make a decision that seeks to avoid serious damage if things
The purpose of the Precautionary Principle is to create an
impetus to take a decision notwithstanding scientific uncertainty
about the nature and extent of the risk, ie to avoid "paralysis
by analysis" by removing excuses for inaction on the grounds
of scientific uncertainty.
10. The precautionary principle should be applied when,
on the basis of the best scientific advice available in the the
time-frame for decision-making:
there is good reason to believe that harmful effects
may occur to human, animal or plant health, or to the environment;
the level of scientific uncertainty about the
consequences or likelihoods is such that risk cannot be assessed
with sufficient confidence to inform decision-making.
11. Such criteria are inevitably judgmental. Nevertheless:
"good reason" to believe that harmful
effects may occur could be demonstrated by. empirical evidence;
by analogy with another activity, product or situation which has
been shown to carry a substantial adverse risk; or by showing
that there is a sound theoretical explanation (tested as necessary
by peer review) as to how harm might be caused; and
"harmful effects" could be gauged by
reference to factors such as severity, irreversibility, uniqueness,
numbers affected, temporal and spatial extent, and knock-on effects
The precautionary principle should be invoked when:
(i) there is good reason, based on empirical evidence
or plausible causal hypothesis, to believe that harmful effects
might occur, even if the likelihood of harm is remote; and
(ii) a scientific evaluation of the consequences and likelihoods
reveals such uncertainty that it is impossible to assess the risk
with sufficient confidence to inform decision-making.
12. Clearly care is needed in making judgements on whether
there is good reason to believe that harmful effects might occur,
and on the extent of scientific uncertainty. "Absence of
evidence of risk" should never be confused with, or taken
as, "evidence of absence of risk". An immediate and
likely consequence of invoking the precautionary principle is
research that seeks to reduce uncertainty. However, where appropriate
and thorough research still finds no evidence of risk, this should
be taken into account in the judgements made.
13. The focus on scientific uncertainty brings out an
important distinction between:
the precationary principle; and
other drivers for caution.
14. For example, even where there is little scientific
uncertainty, Government Departments may be cautionary in situations
(a) the nature of a hazard, or those exposed to a hazard,
reduce the extent of society's toleration of risk, eg where
the consequences of a hazard are known to
be serious or catastrophic, or are associated with high levels
of dread/aversion (eg failure of containment in a nuclear power
station, or exposure to products known to be carcinogenic or highly
those exposed to a hazard are considered to
be vulnerable or disadvantaged (eg children);
reliance on individual choice on the basis
of information provided (eg via warnings or labels) is impossible
or unreasonable (eg air pollution);
the benefits from tolerating a hazard are
not considered to be justified. This could arise because society
considers that the benefits can be forgone, or because there are
acceptable alternatives with lower risk (eg the ban, with very
limited exceptions, on the supply and use of asbestos);
(b) there is a wish to ensure that conventional risk assessment
techniques do not knowingly underestimate risk. Examples of cautionary
conventions in risk assessment include:
the use of uncertainty factors in the assessment
of the health risks from chemicals;
"over-engineering" of bridges and
other major structures.
15. The precautionary principle, therefore, will not
be relevant when acting to address, for example, hazards from
a major chemical plant handling well-known flammable or toxic
products. The regulatory approach to such a plant, however, is
cautionary because: risk is imposed on the general public living
around the plant; the consequences, if the hazard were to be realised,
are potentially serious; such plants are known to produce relatively
high levels of dread/aversion; and the conventional techniques
to estimate risk contours around the plant tend to overestimate
rather than underestimate risk. On the other hand, issues such
as BSE and genetic modification are examples of hazards where
scientific knowledge, even when pushed to the limit, cannot presently
provide conclusive answers about the nature and extent of the
16. In short, the precautionary principle is narrower
than `being cautionary'. At first sight this is counterintuitive
because "principle" implies universality.
The Precautionary Principle:
is narrower than "being cautionary";
is not relevant unless scientific uncertainty
is a significant factor and there is good reason to expect harmful
Extent of precautiongood regulation
17. The "Rio" definition of the precautionary
principle (paragraph 6) is silent on the extent of precaution
required, other than noting that measures should be cost effective.
However, the extent to which the principle requires action erring
on the side of caution is not unlimitedprecaution has to
be balanced against other principles that shape the response to
risk. In practice precaution is bounded by application of the
principles of good regulation . In addition, invocation of
the precautionary principle should be non-discriminatory .
Action in response to the precautionary principle should
accord with the principles of good regulation, ie invocation of
the precautionary principle should:
(a) lead to action that is
proportionate to the required level of protection;
consistent with other forms of action;
targeted to the risk; and
(b) be invoked in a process that is:
accountable to stakeholders and ultimately
to the political process.
18. Although invoking the precautionary principle means
taking action when scientific uncertainty rules out sufficient
information for risk assessment, it doesn't mean that a risk-based
approach is abandoneddecisions continue to be informed
by the best available scientific advice, taking into account the
uncertainties. A risk-based approach is preserved by establishing
19. The precautionary principle is applied in practice
by making assumptions about consequences and likelihoods to establish
credible scenarios. Risk assessment and management can then proceed
on the basis of the assumptions made. In practice a range of alternative
scenarios is usually established. Where possible, the range should
include the most likely and worst case scenarios. Annex 3 describes
the approach in more detail.
20. Application of the precautionary principle requires
considered judgement in selecting the appropriate scenarios on
which to base risk management decisions. In particular:
the assumptions made about consequences and likelihoods
should err on the side of caution and so seek to avoid harmful
effects if things go wrong; but
the bias towards caution should be tempered by
application of the principles of good regulation, particularly
proportionality and consistency in the assumptions made and the
risk management measures selected.
21. In practice erring on the side of caution usually
means giving more weight to the consequences of the risk than
to the likelihood, especially when the consequences are irreversible.
Applying the Precautionary Principle is essentially a matter
of making assumptions to establish credible scenarios, and then
using standard procedures of risk assessment and management to
inform decisions on how to address the hazard.
22. Decision-making requires all relevant factors to
be brought together in selecting the appropriate risk management
optionin the words of the Nice European Council Resolution
(reference 5) "risk management measures must be taken by
the public authorities responsible on the basis of a political
appraisal of the desired level of protection". This presupposes
examination of the benefits and costs of action and inaction,
and that "the examination must take account of social and
environmental costs and of the public acceptability of the different
Openness and transparency
23. Transparency, openness and engagement of stakeholders
are essential in any process of risk assessment and management.
Key aspects of the process include sensitivity to stakeholder
views in framing the risk issue, and stakeholder input in clarifying
uncertainties and contributing to risk management options. However,
where the precautionary principle is invoked and applied, openness
becomes critically important in achieving an outcome that stakeholders
regard as valid. Openness demands candour in exposing, for example:
the information on which risk assessment was undertaken;
the scientific uncertainties and reasoning for
invoking the precautionary principle, and any uncertainty factors
already built into the risk assessment;
the assumptions made in establishing credible
the many factors that influence the choice of
risk management measures.
24. Transparency and openness also help to ensure proportionate
outcomes by exposing where judgements have been made at each stage
of the decision-making process.
Burden of proof
25. The general presumption in western societies is that
the regulator has to demonstrate reasonable grounds to intervene
(Annex 1). However, invocation and application of the precautionary
principle carries a general presumption that the burden of proof
shifts away from the regulator  having to demonstrate potential
for harm towards the hazard creator having to demonstrate an acceptable
level of safety.
26. One consequence is that invoking the precautionary
principle shifts the onus to provide the scientific evidence for
risk assessment from the regulator to the hazard creator. This
is exemplified in licensing or approval regimes imposed to address
more serious hazards considered to merit a strongly precautionary
approach, such as nuclear power generation and pesticides. In
such permissioning regimes the requirements on applicants or holders
of licences or approvals to provide scientific evidence can be
onerous, and can include action to reduce scientific uncertainty.
27. However, in practice the extent to which a permissioning
regime shifts the burden of proof away from the regulator is variable,
reflecting a mixture of policy and scientific factors. For example,
the UK regimes for licensing nuclear power stations and approving
pesticides both require applicants to provide the scientific evidence
needed to assess risk. However, in the nuclear regime the applicant
does a risk assessment and the regulator challenges why risks
cannot be reduced further . In contrast, in the pesticide
regime the regulator undertakes the risk assessment and demonstrates
an acceptable level of safety . In short, flexibility is needed
and the extent to which the burden of proof shifts towards the
hazard creator is determined case-by-case.
28. There are, however, exceptions to the general rule
that invoking the precautionary principle puts the onus on the
hazard creator to provide the scientific information needed for
risk assessment (paragraph 26 above). Where there is significant
value for society in reducing uncertainty, yet there is little
or no prospect of the work being done by the private sector, it
may be appropriate for Departments to act in the public interest
by, for example, undertaking research to plug information gaps.
Examples of such situations include research to establish the
nature and extent of any adverse effects resulting from climate
change, or to investigate a generic range of pharmaceuticals that
has the potential to address a prominent disease or condition.
Unless there are constraints, the presumption should be that:
as a general rule, the hazard creator should provide,
as a minimum, the information needed for decision-making; but
Departments should retain flexibility to determine
"regime-by-regime" the extent to which the burden of
proof should shift towards the hazard creator in demonstrating
presence of risk or degree of safety.
Hierarchy of control measures
29. Invocation of the precautionary principle should
trigger consideration of the whole range of risk management options,
which could include, for example, information and guidance, publicity
campaigns, stronger enforcement and/or larger penalties, and of
course, research to reduce uncertainty. An outright ban on an
activity or product should be a last resort.
30. Nevertheless, within this position regulators should
be able to impose on hazard creators. a preferred hierarchy of
controls that follows established good practice in risk reduction.
For example, good risk management practice in health, safety and
environmental protection starts from the position that, wherever
practicable, it is better to avoid hazards by substitution or
careful process/equipment design than to "bolt-on" measures
to reduce the risks. This would be particularly true for hazards
where there are considerable uncertainties in the estimates of
the risks attached to them.
31. Decisions reached by invoking and applying the precautionary
principle should be:
kept under active review;
revisited when further information that reduces
uncertainties becomes available, and modified as appropriate .
Decisions reached by invoking and applying the precautionary
principle should be actively reviewed to:
ensure that the action taken resulted in what
was intended; and
check whether decisions previously reached need
to be modified to take account of, for example, advances in technology,
new knowledge about the risks from research, or any other information
which may reduce uncertainty in the nature and likelihoods of