The main legal point established in the judgment is the interpretation of the language of the provision, the scheme of Rule 115, and the heading of sub rule 15 to determine the applicability of BS-IV Standards to vehicles with more than four wheels.

The issue raised for consideration in this batch of writ petitions is one and the same, and as such, they are disposed of by this common judgment. The documents referred to in this judgment are the documents produced by the petitioner in WP.(C).No.18028 of 2016.

2. The petitioners are concerns/firms/companies engaged in the trade of automobiles as dealers of manufacturers. Mass Emission Standards to regulate the output of air pollutants from internal combustion engines of automobiles are set by the Central Pollution Control Board and the same are implemented place by place in the country by the Central Government by amending the appropriate provision in the Central Motor Vehicles Rules ('the Rules') framed under the Motor Vehicles Act, 1988 ('the Act'). Sub Rule 15(a) of Rule 115 provides that Bharat Stage IV Mass Emission Standards ('BS-IV Standards') shall come into force in thirteen cities specified therein in respect of four wheeled vehicles manufactured on or after 1.4.2010, except the four wheeled transport vehicles plying on inter-State Permits or National Permits or All India Tourist Permits, within the jurisdiction of the cities mentioned therein. Later, by virtue of the subsequent amendments introduced in the form of provisos to sub rule 15(a) of Rule 115 of the Rules, BS-IV Standards have been implemented in other cities/States also from the dates mentioned in the said provisos. Ext.P1 is the latest amendment to sub rule 15(a) of Rule 115 of the Rules. By virtue of the said amendment, BS-IV Standards have been introduced to a few States including the State of Kerala in respect of four wheeled vehicles manufactured on or after 01.4.2016, except for the four wheeled transport vehicles plying on inter-State Permits or National Permits or All India Permits within the jurisdiction of the said States. According to the petitioners, Ext.P1 amendment applies only to four wheeled vehicles manufactured after 01.04.2016 and the same does not apply to vehicles having more than four wheels. The Transport Commissioner of the State Government has also endorsed the said view initially by issuing Ext.P2 circular to the Registering Authorities under him by directing them to refrain from insisting BS-IV Standards for vehicles having more than four wheels. Later, the Transport Commissioner has issued Ext.P3 circular clarifying that BS-IV Standards are applicable to vehicles having more than four wheels also manufactured on or after 01.04.2016. These writ petitions are filed at that point of time challenging Ext.P3 circular on the ground that Ext.P1 amendment does not apply to vehicles having more than four wheels. Consequential reliefs are also sought in the writ petitions.

3. Heard the learned counsel for the petitioners, the learned Government Pleader as also the learned Assistant Solicitor General.

4. Rule 2(k) of the Rules defines 'M' category vehicles as under:

"(k) Category M" means a motor vehicle with at least four wheels used for carrying Passengers"

Rule 2(o) of the Rules defines 'N' category vehicles as under :

"Category 'N' as motor vehicle with at least four wheels used for carrying goods which may also carry persons in addition to the goods subject to the conditions specified in Para 3.2 of AIS 053-2005, as amended from time to time, till the corresponding BIS specifications are notified under the Bureau of Indian Standards Act, 1986 (63 of 1986)"

Sub rule 15 of Rule 115 of the Rules which deals with the BS-IV Standards for 'M' and 'N' category vehicles, reads thus:

"15. Mass Emission Standards (Bharat Stage IV) for M and N Category vehicles :

(a) the Mass Emission Standards for Bharat Stage IV shall come into force in the National Capital Region and the cities of Mumbai, Kolkata, Chennai, Bangalore, Hyderabad including Secunderabad, Ahmedabad, Pune, Surat, Kanpur and Agra in respect of four-wheeled vehicles manufactured on or after the 1st April, 2010, except the four-wheeled transport vehicles plying on Inter-State perm