In the choking haze of a Delhi winter morning, in 1991, the Supreme Court, in a ruling, presented several apocalyptic scenarios — from the polluting effects of the Gulf War, what-if questions around the USSR carrying out a nuclear test, and memories of the Bhopal Gas Tragedy closer home — to underline that the country ought to get serious about the environment.

“Law alone… cannot help in restoring a balance in the biospheric disturbance. Nor can funds help effectively. The situation requires perception and imaginative planning. It also requires sustained effort and result-oriented strategic action,” the ruling by a three-judge bench headed by then Chief Justice Ranganath Misra said. The SC mooted the idea of setting up a high-powered committee to assess the situation and the petition was “kept pending for monitoring”.

This short seven-page ruling, where the Court seemed to be beseeching rather than passing directives, was to change the course of the national Capital and set a benchmark for environmental jurisprudence in the country. The order came in a plea filed in December 1985 in the landmark M C Mehta v Union of India.

Mehta, then a young lawyer, had approached the Court seeking directions to close hazardous industries operating in the densely populated areas of Delhi and to regulate air pollution from vehicles and thermal units. The case is best known for pushing Delhi’s public transport to transition from the more polluting diesel to CNG.

On March 12, nearly four decades after it intervened, the Court closed the case that has often been held up as an exemplar of its interventionist, public-spirited jurisdiction. A bench headed by Chief Justice of India Surya Kant disposed of the petition to reduce, what the court described as, “massive pendency” and to modernise the legal approach to air quality.

For the man who started it all, the administrative closure of Writ Petition (Civil) No. 13029, the Public Interest Litigation that he filed in 1985, changes little.

“I don’t have a personal reaction because this is not my personal case,” says the 79-year-old lawyer from his daughter’s home in Delhi’s Neeti Bagh, where he sat poring over three volumes of his book, In the Public Interest: Landmark Judgements & Orders of the Supreme Court of India on Environment & Human Rights — “to prepare for the interview” and because “I hope to revise the book some day”.

“The case has wider importance and ramifications. We are living under clouds of dust, air pollution, water pollution and groundwater pollution. We have destroyed our rivers; we have destroyed everything. I would be very happy if even one river or stream is clean in this country,” says the man whose name is synonymous with environmental jurisprudence in the country.

Born in 1946 in Rajouri, J&K, Mehta recalls being active in social movements since his youth. As a young man in Jammu, he ran a weekly newspaper called Presager, which focused on social and environmental issues, before studying law at Jammu University and practising at the Jammu and Kashmir High Court.

In 1983, he moved to Delhi to practise at the Supreme Court, working out of the chambers of some lawyer-friends and a house his in-laws owned in Lajpat Nagar. Mehta recalls that his initial cases were mostly appeals against decisions of the J&K High Court. “I took up a lot of social and public interest matters. I earned just about enough to make ends meet,” he says.

The turning point came soon after, in the form of the oleum gas leak case of 1985.

“Some labourers and union representatives from the Shriram food and fertiliser factory near Punjabi Bagh in West Delhi came to me, complaining that it was very difficult to even go near the area due to the pollution and asking me to take this up in court. I went to the Zakhira area in Punjabi Bagh to see it for myself. The locals told me they couldn’t sleep properly at night because of the thick smoke. This was right after the 1984 Bhopal gas tragedy, so people were already terrified that something similar would happen,” he says. “After a proper investigation, I filed a writ petition in the Supreme Court.”

The court didn’t hear the matter immediately. About a month later, on December 4, 1985, exactly a year after the Bhopal gas tragedy, disaster struck. Toxic oleum gas, or fuming sulphuric acid, leaked out of the Shriram factory, killing one and leaving many injured.

Recalling the chaos of that day, Mehta says, “I was in the Court for another case. Suddenly, lawyers started running through the corridors shouting, ‘Run! There’s a gas leak!’ I ran to my locker, pulled out the slip for the petition I had filed a month earlier and rushed to the court master.”

The Court agreed to hear Mehta’s plea on priority. While in February 1986, it allowed the company to temporarily restart its plant, subject to stringent safety conditions, later that year, in a landmark judgment on December 20, a five-judge bench established the principle of “absolute liability” for hazardous industries, holding them liable to compensate for any harm caused by their activities.

Spurred by the case, Mehta filed several other PILs in 1984-85. Data that the Ministry of Law and Justice presented in Lok Sabha earlier this month revealed that of the 698 PILs pending in the Supreme Court for over a decade, the oldest three were by Mehta.

Four of the cases Mehta filed — popularly known as the Taj Mahal pollution case, the Ganga pollution case, the Delhi de-industrialisation case (“sealing” of commercial establishments) and the Delhi vehicular emissions case (which was recently closed) — ended up being bigger than the petitioner whose name they carried.

For a judiciary that was reeling from backlash on its position during the Emergency, these populist causes would help regain public confidence in the institution. The court-as-catalyst image continued for decades through public interest litigation.

But it was in Mehta’s vehicular pollution case, Writ Petition (Civil) 13029/1985, that sustained the Court’s oversight for over four decades. It was around this time that Delhi’s vehicular traffic had begun to boom: as of March 1982, there were 5.92 lakh vehicles (65% of those two-wheelers), projected to rise to 13.5 lakh by 1990 .

The Court’s 1986 order, agreeing to hear the plea, linked the right to life under Article 21 of the Constitution to clean air, keeping the writ alive for oversight. Its “pending for monitoring” status, meaning that the court would periodically hear the case to ensure the implementation of its order, built itself into a novel judicial tool — the continuing mandamus. Unlike a standard court order that resolves a dispute and closes a case, a continuing mandamus allows the court to keep a case open indefinitely, while issuing periodic directions to monitor executive compliance.

In the vehicular pollution case, the Court over the years issued the longest continuing mandamus to combat air quality in Delhi. Case records show that over 1,000 court orders were issued.

This perpetual monitoring, while innovative, raised questions: was the court, through its writ of mandamus, encroaching on executive turf, or filling a vital governance vacuum?

Mehta defends the court’s prolonged oversight. “Who would think a case would go on for so long? But what is wrong with that?” he asks. “The concept of a continuing mandamus exists for a reason — if there is no compliance, the honourable judges keep the matter open to monitor it. How can we look at it differently when it is not about one individual’s safety, but the safety of millions of people?”

Out of this one case came a string of reforms and environmental policies that shape air and pollution management to this day, in Delhi and beyond — from the court mandating 13 highly polluted Indian cities, besides Delhi, to implement clean air action plans to banning firecrackers across the National Capital Region. The Court also supervised the construction of two big road projects, the Western and Peripheral Expressway, which would reroute vehicular traffic away from Delhi. This 2001 order also included restrictions on the entry of heavy vehicles into the city, which continues to this day.

The biggest push from the Court came in the form of directions to the Sheila Dikshit-led Congress government in Delhi to shift the city’s public transport to CNG. Orders from 2001 are littered with ultimatums, threats and extension of timelines to the government. The constant monitoring of the court ensured no room for the government to delay the Court’s orders.

Shailja Chandra, former Chief Secretary of Delhi, who took over in February 2002 and oversaw the transition of the city’s public transport fleet from diesel to CNG, says, “This was one of the few success stories in policy implementation that I have seen in my career. There was the BJP-led NDA government at the Centre and the Sheila Dikshit-led Congress government at the state, but there was no quarrelling because the SC was monitoring the whole issue.”

A former bureaucrat who was involved in the exercise says, “Those days, there would be serpentine queues for CNG in Delhi… It would have been very difficult for any government to make this policy shift on its own. The Court also found a determined Chief Minister to ensure the change happened. The government could reason with the public that they were acting on the instructions of the Court.”

The result was a dip in pollution levels from the alarming 1990 levels. A 2014 study by EPCA noted that the annual average PM10 levels in Delhi reduced by about 16% between 2002 and 2007. However, the gains over the years were minimised as private vehicles swelled, while public transport remained the same.

Beyond these directions as part of the case, orders also show that the Court kept the government on its toes with its observations. “In that case [Bhopal gas tragedy], the nation, including the Union of India, was rightly agitated and sought action and compensation from the multinational company… Here, in the case of CNG, the shoe is on the other foot because the government is not facilitating measures for clean air and water, including the supply to CNG or any other clean, unadulterated fuel,” the Court said in an April 2002 order.

Even in 2015, then CJI HL Dattu had air quality monitors installed within the courtrooms and pulled up the government when PM2.5 levels rose during the winters.

Advocate Ejaz Maqbool, who appeared in the case since 2001, says that the “city would have been a furnace much earlier if not for the Court’s intervention.”

However, critics of the court intervention flag an “institutional lethargy” that has developed. “There is no burden on judges in any other country to be responsible for clean air and clean water. The responsibility lies with the executive, which has done an abysmal job of it,” senior advocate Shyam Divan told The Indian Express.

Despite his historic legal victories – which earned Mehta the Goldman Environmental Prize in 1996 and the Ramon Magsaysay Award in 1997 – Delhi’s air continues to remain hazardous every winter. Mehta places the blame on the executive.

“We cannot blame the courts. The courts have done their part; they have passed judgments,” he says. “The problem lies in implementation and enforcement, which is the job of the executive. There is the Centre, state governments, state pollution control boards — an entire structure exists.”

The way out, he says, is to increase judicial infrastructure that can take up environmental cases. Five benches of the National Green Tribunal can’t serve a population of 1.4 billion, he says, adding, “We need dedicated fast track environmental courts in every district.”

In recent years, Mehta has stepped back from active court appearances, given his health and family commitments. Instead, he has been focusing on updating his legal writings and making it more accessible to people.

Choosing public interest litigation over representing corporations is a choice he does not regret. “When a poor man comes to me saying his fields are ruined because of toxic water, what can I ask him to pay? The industries he is fighting against hire top lawyers and pay them whatever they ask. There is no comparison,” Mehta says. “You have to choose where you stand.”