Retrospective unjust enrichment provisions cannot reopen a final excise refund already granted before those rules began.

Provisions introducing unjust enrichment and related recovery machinery under the Central Excise Act do not apply retrospectively to a refund that was already finally and unconditionally granted before their commencement. A refund made in 1989 could not be reopened as an erroneous refund under later Sections 11B and 11D, because the matter did not arise from a pending refund claim and the amount had already been paid out. The settled refund therefore remained intact, and recovery based on unjust enrichment was not sustainable.

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Issues: Whether a refund of excise duty granted before the insertion of the unjust enrichment provisions could be reopened as an erroneous refund and recovered under the Central Excise Act, and whether Sections 11B and 11D applied to such a completed refund.

Analysis: The refund in question had been granted in 1989, whereas the unjust enrichment requirement in Section 11B(2) and the machinery in Section 11D came into force only on 20-9-1991. The Court held that these later provisions could not be applied retrospectively to a refund already made and finalized. It further held that the matter did not arise from a refund application under Section 11B, and the amount had already been refunded, so Section 11D also had no role. Relying on earlier decisions, the Court reiterated that once assessment or adjustment has been finally completed under the applicable excise procedure, recovery cannot be reopened by invoking unjust enrichment.

Conclusion: The recovery based on unjust enrichment was not sustainable, and Sections 11B and 11D did not apply to the completed refund.

Final Conclusion: The assessee was entitled to retain the refunded amount, and the demand confirmed by the authorities was set aside.

Ratio Decidendi: Provisions introducing unjust enrichment and related recovery machinery do not apply retrospectively to a refund that was already finally and unconditionally granted before those provisions came into force.

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