Principle 21 as the No-Harm Rule in International Environmental Law
Principle 21 of the Stockholm Declaration states the basic bargain of international environmental law: a State has sovereign authority over its natural resources, but that authority is limited by responsibility for environmental injury caused beyond its borders or beyond national jurisdiction.
The principle joins two ideas that must always be read together: permanent sovereignty over natural resources and the duty to prevent transboundary environmental harm.
Its first clause protects the right of each State to choose its own environmental and development policies, exploit its forests, minerals, waters, fisheries, energy resources, and land, and regulate economic activity within its territory.
Its second clause prevents sovereignty from becoming a license to injure other States, shared resources, or global commons areas such as the high seas and other areas beyond national jurisdiction.
Although the Stockholm Declaration is not itself a treaty, Principle 21 is treated as an authoritative expression of the no-harm principle and due diligence obligation that now informs treaty interpretation, customary international law, and domestic environmental adjudication.
Operative Content
The principle is not merely aspirational; it supplies a legal standard for judging whether a State has exercised environmental sovereignty responsibly.
- Right: a State may exploit and manage its own natural resources according to its own environmental and development policies.
- Limit: the State must ensure that activities within its jurisdiction or control do not cause environmental damage to other States or areas beyond national jurisdiction.
- Standard: the State must exercise due diligence, which means reasonable regulatory, preventive, supervisory, and cooperative measures proportionate to the risk.
- Scope: the duty covers activities of government agencies, State enterprises, private entities, and persons when the activity is within the State's jurisdiction or control.
- Threshold: international responsibility generally requires a risk or occurrence of significant transboundary environmental harm, not every minor, speculative, or purely local impact.
Sovereignty Over Natural Resources
Principle 21 recognizes that environmental protection cannot erase the equality and independence of States.
A developing State may pursue mining, infrastructure, agriculture, energy generation, fisheries, reclamation, or industrialization as part of national development, provided that the pursuit is regulated in a manner consistent with environmental responsibility.
The sovereignty protected by Principle 21 is functional, not absolute; it allows a State to decide how resources will be used, but it does not permit the State to externalize serious environmental costs to another State or to global commons areas.
For the Philippines, this aspect is especially relevant because the State manages archipelagic waters, marine resources, minerals, forests, biodiversity, coastal zones, and energy projects while also dealing with neighboring States and shared marine ecosystems.
Domestic ownership, licensing, concessions, permits, or administrative approvals do not by themselves answer the international question; an activity may be lawful under domestic authorization yet still create international responsibility if the State fails to prevent significant cross-border or common-area harm.
Responsibility Not to Cause Environmental Damage
The duty under Principle 21 is commonly described as the no-harm principle.
The obligation is not an absolute guarantee that no environmental damage will ever occur; it is an obligation to take all reasonable measures that a prudent State would take under the circumstances.
The required level of care rises with the gravity of possible harm, the likelihood of harm, the sensitivity of the receiving environment, the technical capacity of the State, and the degree of control the State has over the risky activity.
A State breaches the principle when it knowingly permits, authorizes, encourages, or fails to regulate activities that create a foreseeable risk of significant environmental injury outside its territory or in areas beyond national jurisdiction.
The duty applies even when the immediate actor is private, because international law looks at whether the State exercised adequate regulation, supervision, enforcement, and cooperation over persons and activities subject to its jurisdiction or control.
Jurisdiction or Control
The phrase jurisdiction or control is broader than territorial ownership.
It includes activities within land territory, internal waters, archipelagic waters, territorial sea, airspace, installations, vessels, and other situations where the State can reasonably regulate or prevent the harmful conduct.
Control may also arise where a State authorizes a project, issues a permit, owns or operates the facility, finances the activity, exercises regulatory supervision, or has the practical ability to stop or condition the conduct.
The principle therefore reaches domestic decisions that have external environmental consequences, such as marine pollution, hazardous waste movement, cross-border air pollution, offshore resource extraction, biodiversity loss in shared ecosystems, and activities affecting migratory species or the high seas.
For an archipelagic State, the concept is important because environmental harm may travel through water currents, air currents, fishery systems, coastal habitats, or maritime routes rather than through a land boundary.
Due Diligence Measures
Due diligence under Principle 21 is measured by conduct, not by the mere existence of environmental statutes.
A State must adopt and enforce a functioning system that can identify, prevent, reduce, and respond to significant environmental risks created within its jurisdiction or control.
| Measure | Legal significance |
|---|---|
| Environmental impact assessment | Identifies whether a proposed activity may cause significant adverse environmental effects, including transboundary or common-area effects. |
| Licensing and permitting | Allows the State to condition, restrict, suspend, or deny activities that create unacceptable environmental risk. |
| Monitoring and reporting | Prevents paper compliance by requiring continuing observation of emissions, discharges, extraction, waste, and ecological impacts. |
| Notification and consultation | Allows potentially affected States to evaluate risks, give views, and cooperate before harm occurs. |
| Emergency response | Requires prompt action when pollution, spills, hazardous releases, or other environmental incidents threaten external harm. |
| Enforcement | Shows that environmental duties are legally real through inspections, penalties, suspension, closure, remediation, or prosecution. |
An environmental impact assessment is especially important for activities with a plausible risk of significant adverse transboundary impact because prevention is the central method of Principle 21.
Scientific uncertainty does not automatically excuse inaction when the possible damage is serious or irreversible; in such situations, preventive and precautionary measures become part of reasonable due diligence.
Damage to Other States
Damage to another State includes environmental injury affecting its territory, population, natural resources, marine areas, air quality, waters, biodiversity, food security, health, property, or legally protected environmental interests.
The harm must be more than trivial; the usual concern of international law is significant damage, substantial risk, or serious interference with another State's rights.
The rule does not require hostile intent, because environmental responsibility can arise from negligent regulation, defective permitting, inadequate monitoring, failure to warn, or failure to respond.
Foreseeability is central: a State is expected to act when it knows or should know that an activity under its jurisdiction or control creates a significant risk of external environmental damage.
Good faith cooperation is also central, because environmental harm often crosses borders before responsibility can be formally adjudicated.
Areas Beyond National Jurisdiction
Principle 21 also protects environmental areas that no State may treat as a private dumping ground.
Areas beyond national jurisdiction include spaces and resources not subject to the sovereignty of any one State, most notably the high seas and other common-area environments recognized by international law.
The reference to areas beyond national jurisdiction is what makes Principle 21 more than a neighbor-relations rule; it is also a rule of stewardship over common environmental interests.
Activities such as marine pollution, illegal or destructive fishing, seabed activities, atmospheric pollution, and waste disposal may implicate this aspect when their effects extend into common areas.
The duty protects the international community's interest in preventing serious degradation of shared environmental systems even when no single injured State can show exclusive territorial damage.
Domestic Relevance in Philippine Law
The Philippines receives generally accepted principles of international law as part of the law of the land through the incorporation clause in Article II, Section 2 of the Constitution.
The Constitution also recognizes the people's right to a balanced and healthful ecology in accord with the rhythm and harmony of nature under Article II, Section 16.
These provisions allow Philippine courts and agencies to read environmental statutes, administrative permits, and remedies in harmony with international environmental principles such as prevention, precaution, intergenerational equity, and the no-harm principle.
Principle 21 does not itself create a complete domestic cause of action for every environmental grievance, but it may inform the interpretation of constitutional rights, environmental statutes, administrative discretion, and judicial remedies.
Philippine environmental governance implements the same preventive logic through the environmental impact statement system, pollution control laws, protected area laws, fisheries regulation, waste regulation, mining regulation, climate policy, and remedies under the Rules of Procedure for Environmental Cases.
The writ of kalikasan reflects a domestic remedial structure for environmental damage of a magnitude prejudicial to life, health, or property in two or more cities or provinces, but its focus is domestic judicial protection rather than diplomatic responsibility between States.
Relationship With Other Environmental Principles
Principle 21 is best understood as the foundation on which several operational environmental principles rest.
| Related principle | Connection to Principle 21 |
|---|---|
| Prevention | Requires action before significant environmental harm occurs because post-damage repair is often impossible or inadequate. |
| Precaution | Supports protective measures despite scientific uncertainty when serious or irreversible harm is plausibly threatened. |
| Cooperation | Requires States to exchange information, notify, consult, and coordinate on activities with external environmental risk. |
| Sustainable development | Balances resource use and environmental protection without allowing development to impose unlawful external harm. |
| Polluter pays | Internalizes environmental costs so that harmful activities do not shift their burdens to the public, other States, or common areas. |
| Intergenerational equity | Treats environmental stewardship as a duty owed not only to present communities but also to future generations. |
These principles do not replace Principle 21; they help determine what responsible environmental sovereignty requires in concrete situations.
State Responsibility
When a State breaches the no-harm duty, ordinary rules of State responsibility may require cessation of the wrongful conduct, assurances of non-repetition, remediation, compensation, or other appropriate reparation.
International responsibility requires attribution to the State or failure by the State to exercise due diligence over activities within its jurisdiction or control.
Private conduct is not automatically conduct of the State, but the State may still be responsible if it failed to regulate a dangerous activity, ignored known risks, tolerated non-compliance, or failed to enforce environmental controls.
Causation remains necessary because a claimant must connect the activity under the respondent State's jurisdiction or control with the significant environmental damage alleged.
Where harm is imminent rather than completed, the appropriate legal focus is prevention, suspension, modification of the activity, information-sharing, consultation, and emergency measures.
Limits of the Principle
Principle 21 does not prohibit all pollution, all resource extraction, or all environmentally risky development.
It does not convert international environmental law into strict liability for every accidental spill or unforeseen ecological effect.
It does not allow one State to dictate another State's entire development policy merely because the activity has environmental consequences.
It does, however, deny any claim that domestic sovereignty alone can justify serious, foreseeable, and preventable environmental damage to other States or to areas beyond national jurisdiction.
The controlling inquiry is whether the State acted as a responsible sovereign: assessing risk, regulating actors, preventing significant harm, cooperating in good faith, enforcing environmental duties, and responding promptly when damage threatens or occurs.