JUDGMENT

S.B. Sinha J.—

1. Leave granted. Introduction:

2. Doctrine of unjust enrichment, as opposed to doctrine of retention, is the core question involved herein. It arises out of a judgment and order dated 21.10.2008 passed by a Division Bench of the Bombay High Court in Writ Petition No. 22 of 2006. Background facts:

3. Respondent is a company registered and incorporated under the Companies Act. It inter alia is engaged in the business of operating a multiplex theatre, commonly known as Fame Adlabs in the town of Mumbai for screening of films in the said theatre. Indisputably, the provisions of the Bombay Entertainments Duty Act, 1923 (for short “the Act”) are applicable to the said multiplex theatre. The State of Maharashtra, however, adopted a policy decision to provide certain exemptions in the matter of payment of entertainment duties. Entertainment duty is payable at the rate of 45% on payment for admission by the proprietors so far as the multiplex theatres constituted within the limits of the Brihan Mumbai Municipal Corporation are concerned.

4. Respondent availed the said exemption. It, however, even during the period for which it was not liable to pay any duty or duty a