New Delhi, Nov. 10 -- The Supreme Court had set a narrow two-hour window for bursting firecrackers on Diwali, permitted only certified "green" crackers, and made it clear that the restrictions would be strictly enforced. Yet, as the evening wore on, fireworks continued across Delhi well past the deadline, with several neighbourhoods reporting bursts until 3am.

The widespread violations, residents said, took place despite police personnel being deployed on the ground, raising questions about how effectively the restrictions were enforced.

The problem was not merely that people ignored the rules. Experts said allowing green crackers in the Capital also made enforcement more difficult, as once illegal conventional firecrackers reached cons...