Your lordships, before banning diesel cars, did you look inside your garage?

Any retrospective piece of legislation or ruling can be irritable to say the least. It is always unforeseen and because as an individual you cannot undo what has been done, it can make anybody feel powerless. The reaction to this is always abrasive.

If you are a big corporate like Vodafone, you drag the offending party (in their case, the government) to court.

If you are a sundry diesel cab owner in Delhi, all you can do is protest by blocking roads that lead to jams and cause inconvenience to the public at large. When the offending party here (for them) is the highest court of the land, what other option are they left with?

So two days after the Supreme Court ruling that prohibits any diesel taxi from plying in Delhi, the aggrieved drivers took to the streets causing traffic snarls all across Delhi.

Monday (May 2) was the first working day after the end of the second phase of Kejriwal government's Odd-Even scheme and traffic was expected to be high anyway.

There is little the taxi drivers can hope for - reversal of a judgement in the face of unrest would set a dangerous precedent - but the agitation is unlikely to end anytime soon.

Diesel to CNG isnt as easy as petrol to CNG?

What is the bone of contention? High pollution levels in Delhi, often referred to as the most polluted city in the world, is a headache for everybody. The government, courts and sundry NGOs have zeroed in on diesel cars as the main culprits.

In December last year, SC had banned registration of diesel cars with engine size of more than two litre in Delhi NCR region till March 31, 2016. That ban remains in force now.

At the same time, the court extended the deadline for converting all diesel cabs into CNG by a month to April 30, 2016. That deadline got over on Saturday and hence the protest.

The judgment and the underlying notion that only diesel is to be blamed for all ills of Delhi air is problematic on many counts. Unlike petrol to CNG that can cost as little as Rs 30,000, converting a high compression diesel engine into CNG is problematic.

It requires fundamental changes in the engine of the car and is an expensive, time-consuming process. Depending on the car, it can cost as much as Rs 1.5 lakh and can take upto ten days.

A cab driver, already burdened with a car loan - mind you, diesel cars also cost more than petrol - can ill afford that kind of expense.

Is diesel really bad?

There is at least some truth that diesel is a polluting fuel. Except a hydrogen fuel or an electric car, no vehicle is absolutely non-polluting. Compared to a petrol car, a diesel car emits upto 22 times more Suspended Particulate Matter (SPM) - those tiny particles that easily penetrate your lungs, heart and even brain.

It is also known to emit four times more nitrogen dioxide. However, a diesel car emits 15 per cent less carbon dioxide than petrol and since it a more efficient fuel (it burns more than petrol), it also gives a higher fuel economy. That negates some of the pollution as you are using less fuel to travel the same distance.

Take a side on any of the fuels depends on what you wish to curb. If carbon dioxide is the main villain, like Europe believed it was in the 90s, then diesel technology gets a push. If SPM or nitrogen dioxide is bothering you, clamp down on diesel. Which is what the government is trying today.

There is a raging debate whether that is the right way to go. A study done by IIT Kanpur says diesel engines (cars and commercial vehicles) contribute only 2 per cent of the overall SPM in Delhi's air. So by clamping down on diesel cabs - which is only a small part of the overall pie - will serve absolutely no purpose.

At the same time, it is obvious that new diesel cars pollute only a fraction of their older cousins. A diesel car bought in Delhi in the recent past compared to one bought seven years ago when BS III was in place, emits 50 per cent less SPM and NOx and 20 per cent less carbon emission.

The difference is even more glaring when compared to BS II or BS I emission cycles. And those cars are still plying on our roads.

In effect, banning new cars, that can, in fact, be fitted with a catalytic converter and be made Euro V and VI ready, is like punishing a son for his father's crimes.

What do the judges own?

Which brings us to the question of what the judges themselves own. According to the Supreme Court website, the chief justice of India, TS Thakur owns a Premier 118 NE, a car that went out of production in 2001.

Its a car that belongs to the pre-Bharat Stage emission regime. As per an NGT order from November 2014, it cannot ply on Delhi roads even with a fitness certificate as it is over 15 years old. Mr Thakur would do well to junk his car.

For the same reason, his colleague Justice Anil R Dave, should ask his spouse to junk her 1998 model Hero Honda motorcycle, 1984 Sunny scooter and 2000 model Hyundai Santro while Justice Jagdish Singh Khehar should junk his 1996 model Daewoo Cielo.

Similarly, Justice FM Ibrahim Kalifulla's spouse should not be able to use her 1961 model Fiat that was purchased only in 2006. And Justice Kurian Joseph should be aware his 2004 Maruti Esteem is fast nearing its sell-by date.

All the judges get official cars for their use, so obviously their own cars hardly get to feel the tarmac. Yet, many of them at the SC as well as Delhi High Court have not declared the type of vehicles they or their dependents own.

It would be difficult to believe nobody owns a diesel car or a car that, just like in the cases above, does not comply with the orders the judges or their colleagues themselves dole out, day in day out.

Practice what you preach is an old saying. Sometimes it can be tricky. Or as the judges would themselves say, ignorance is not an excuse.

While they are at it, maybe they can think about what a driver, who earns less than a tenth of what they make, is supposed to do with a taxi for which he has to pay EMI but can't ply anymore in Delhi.