## Facts

- In 1986, M.C. Mehta, a public-interest lawyer, began litigation in the Supreme Court of India challenging severe air pollution in Delhi and seeking court-directed action against vehicular emissions.
- The case proceeded as a long-running public-interest matter with continuing directions to central and local authorities responsible for transport regulation, fuel policy, and pollution control.
- During the proceedings, an environmental regulatory authority recommended that Delhi’s bus fleet convert from diesel to compressed natural gas (CNG) to reduce harmful emissions, particularly fine particulate pollution.
- Acting on these recommendations, the Supreme Court ordered conversion of Delhi’s buses to CNG and set deadlines, while retaining supervision to monitor compliance.
- The Union of India obtained two extensions of the conversion deadline. After those extensions, it again asked the Court to extend or modify the order, arguing that CNG was not available in sufficient quantity and that infrastructure constraints made full conversion impracticable.
- Mehta and opposing submissions contested the request, arguing that delays would prolong serious health harms from diesel emissions and that supply and distribution planning were within governmental control.

## Issues

1. Whether the Union of India showed sufficient grounds to justify a further extension or modification of the Court’s earlier directions requiring Delhi’s buses to convert to CNG.
2. Whether asserted constraints in CNG supply and distribution justified continuing operation of diesel buses in Delhi in place of the Court-ordered CNG regime.
3. Whether, given constitutional and statutory duties relating to public health and environmental protection, the State could treat administrative difficulty as a reason to postpone compliance with pollution-control directions.

## Decision

- The Court denied the Union of India’s request for a further broad extension or dilution of the CNG conversion requirement for Delhi’s bus fleet.
- The Court reaffirmed that the CNG conversion directions remained binding and that compliance could not be deferred based on generalized claims of scarcity or inconvenience.
- The Court accepted the regulatory assessment that CNG use in buses materially reduces pollution levels that affect public health, and treated that objective as controlling in deciding whether to relax prior orders.
- The Court continued its supervisory role and permitted only limited, time-bound measures aimed at preventing disruption of essential public transport while the conversion was completed, without changing the required end result.

## Legal Principles

- Clean air and protection from serious pollution-related health risks fall within the constitutional protection of life, and the State has a duty to act against conditions that endanger public health.
- Directive Principles and environmental provisions inform governmental obligations to improve public health and protect the environment, and they support court enforcement when executive implementation fails.
- In a continuing public-interest matter addressing persistent environmental harm, the Court may issue ongoing directions and retain jurisdiction to secure compliance with measures necessary to protect health.
- Repeated requests to postpone compliance with pollution-control orders require strong, concrete justification; administrative difficulty, cost, or planning failures are not enough where delay prolongs major public health harms.
- When compliance depends on government-controlled planning choices (including allocation and supply arrangements for cleaner fuel), the State cannot rely on self-created constraints to avoid court-ordered environmental safeguards.

## Conclusion

Mehta v. Union of India (2002) is part of the Supreme Court’s long-running Delhi air-pollution litigation in which the Court required conversion of the city’s buses to CNG and, when the Union of India sought another extension based on asserted CNG shortages, refused to dilute the mandate, treating protection of public health and the environment as a constitutional duty and keeping the case under continuing judicial supervision until implementation was completed.


Mehta v. Union of India, 2 Law Reports of India 1 (2002)