JUDGMENT

KHANNA, J.:— The short question which arises for determination in this appeal on certificate by Damodar Valley Corporation against the judgment of Patna High Court dismissing the writ petition filed by the appellant is whether the appellant is liable to pay electricity duty under Bihar Electricity Duty Act) 1948 as amended by Bihar Electricity Duty (Amendment) Act, 1963. The High Court answered the question in the affirmative against the appellant.

2. The appellant is a corporation established under the Damodar Valley Corporation Act, 1948 for the development of the Damodar valley in the State of Bihar and West Bengal. One of the functions of the appellant is the promotion and operation of schemes for the generation, transmission and distribution of hydro-electric and thermal electrical energy. Bihar Electricity Duty Act, 1948 (Bihar Act 36 of 1948) (hereinafter referred to as the principal Act) was published in the Bihar gazette on October 1, 1948. It was an Act for the levy of duty on the sales and consumption of electrical energy in the province of Bihar, Material part of Sections 3 and 4, as they stood before the amendment made in 1963, read as under.

"3. Incidence of duty - (1) There shall be levied and paid to the State Government on the units of energy consumed or sold, excluding losses of energy in the transmission and transformation, a duty at the rates specified in the First Schedule :

Provided that no duty shall be leviable on units of energy :-

(i) ........... ............

(ii) ........... ............

(iii) ........... ............

(iv) ........... ............

(v) consumed by, or in respect of, or sold for consumption in any -

(a) mine, as defined in the Indian Mnes Act, 1923;

(b) industrial undertaking;except to the extent specified in the Second Schedule;

(vi) ........... ............

(2) ........... ............

4. Payment of duty - (1) Every licensee shall pay every month to the State Government at the time and in the manner prescribed the proper duty payable under Section 3 on the units of energy consumed by him or sold by him to the consumer.

(2) Every license may recover from the amount which falls to be paid by the licensee as duty in respect of energy sold to the consumer.

(3) ............ ............

(4) ............ ............

(4a) ........... .............

(5) ............. ............ "

The principal Act was amended by Bihar Electricity Duty (Amendment) Act. 1963 (Bihar Act 20 of 1963) (hereinafter referred to as the amending Act). The amending Act received the assent of the President on December 4, 1963 and was published on December 17, 1963. By Section 2 of the amending Act, new Section 3 was substituted for the old Section 3. Material part of new Section 3 read as under:

"3. Incidence of duty,- (1) Subject to the provision of sub-section (2) there shall be levied and paid to the State Government on the units of energy consumed or sold, excluding losses of energy in transmission and transformation, a duty at the rate of rates specified in the Schedule.

(2) No duty shall be leviable on units of energy -

(a) ............ .............

(b) ............ ..............

(c) .............. .............

(d) .............. .............

(e) consumed by the Damodar Valley Corporation for the generation, transmission or distribution of electricity by that Corporation;

(1) .......... .........

(3) ......... ..........

Amendment was also made in the First Schedule of the principal Act. The relevant part of the schedule read as under:

"THE SCHEDULE

(See Section 3.)

RATES OF DUTY.

A. For a mine or an industrial undertaking, save in respect of its premises used for residential or office purposes. Such rate or rates not exceeding 2 nayw paise per unit of energy as may, from time to time, be fixed by the State Government with the previous consent of the President, by order in this behalf."

3. In the writ petition the appellant prayed for quashing three notices dated February 10, 1965 issued by the Superintendent of Commercial Taxes Gi