Chittaranjan Das v. State of Orissa, (2011) 7 SCC 167 at page 170
14. We are of the opinion that in a case in which sanction sought for is refused by the competent authority, while the public servant is in service, he cannot be prosecuted later after retirement, notwithstanding the fact that no sanction for prosecution under the Prevention of Corruption Act is necessary after the retirement of the public servant. Any other view will render the protection illusory. Situation may be different when sanction is refused by the competent authority after the retirement of the public servant as in that case sanction is not at all necessary and any exercise in this regard would be action in futility.
