DELHI CLOTH & GENERAL MILLS COMPANY LTD. & ANR. vs RAJASTHAN STATE ELECTRICITY BOARD & ANR.

The Supreme Court examined the powers of the State Electricity Board under Sections 49A and 49B of the Electricity Supply Act, 1948, regarding unilateral tariff adjustments. The Court upheld the High Court's ruling that the Board's imposition of a 15% general surcharge was ultra vires due to the existing statutory agreement with the appellants, which restricted such unilateral changes. The Court affirmed that the Board could not revise tariffs retroactively without breaching the agreement, thereby reinforcing the doctrine of promissory estoppel in this context.