Banning of diesel vehicles of more than 10 years old by ngt

Yes a tribunal cannot declare law ultra vires.

Even the said section of Motor Vehicles Act looks like it has been enacted arbitrarily, without application of mind, without giving due weight to relevant facts, infringing natural justice and equality before law. Following thoughts need lawful answers -

Every motor vehicle brand new or old has to get pollution under check certificate periodically. This means even a brand new motor vehicle may fail the test.

When an old vehicle is satisfying emission norms, where is the problem or injury?

Who is getting benefited by this 15 year or any year limit whatsoever? The sale of automobile manufacturers may likely get boost because every 15 years everyone is compelled by the enactment to scrap the old motor vehicle and buy a new one. But the pocket of common man will surely directly or indirectly suffer.

This 15 year or any year limit rests on the faulty basis that no matter how well the automobile has been maintained or repaired, or even if the parts that are responsible for gaseous emission are replaced by new, it can never pass the standards of pollution control norms. This is at variance with real facts.

Very true. The ultimate beneficiary appears to be the Vehicle Manufacturer and the Government itself which collects taxes on each and every registration. Rather than enforcing the prevalent rules and regulations regarding pollution check or making them more stringent, this appears to be a short-cut to achieve what could not have been achieved by enforcement of the existing rules and regulations. Every time, it is the general public who have to bear the brunt. Sacrifices may be made only if they are really required.

Dear Querist, you may see that you have stated that the NGT has banned the new registration of vehicles of that category, the NGT has not made a mention of existing vehicles.  If you feel the ruling is unjustified and ultra vires, you may move a PIL for the social cause.