Judgment :- R. JAYASIMHA BABU, J. The Tribunal has held that the question of unjust enrichment has not arisen for consideration and that restrictions imposed by Section 11B of the Central Excise Act with regard to refund of duty will not apply to claims for refund when the matter is still at the stage of provisional assessment, and no final assessment to duty has been made. 2.A Constitution Bench of the Supreme Court in the case of Mafatlal Industries Ltd. v. Union of India in the majority judgment at paragraph 95 has made the following observations : "Rule 9B provides for provisional assessment in situations specified in Clauses (a), (b) and (c) of sub-rule (1). The goods provisionally assessed under sub-rule (1) may be cleared for home consumption or export in the same manner as the goods which are finally assessed. Sub-rule (5) provides that" when the duty leviable on the goods is assessed finally in accordance with the provisions of these Rules, the duty provisionally assessed shall be adjusted against the duty finally assessed, and if the duty provisionally assessed falls short of or is in excess of the duty finally assessed, the assessee shall pay the deficiency or be entitled to a refund, as the case may be, "Any recoveries or refunds consequent upon the adjustment under sub-rule (5) of Rule 9B will not be governed by Section 11A or Section 11B, as the case may be. However, if the final orders passed under sub-rule (5) are appealed against - or questioned in a writ petition or suit as the case may be, assuming that such a writ or suit is entertained and is allowed/decreed - then any refund claim arising as a consequence of the decision in such appeal or such other proceedings, as the case may be, would be governed by Section 11B. It is also made clear that if an independent refund claim is filed after the final decision under Rule 9B(5) re-agitating the issues already decided under Rule 9B - assuming that such a refund claim lies - and is allowed, it would obviously be governed by Section 11B. It follows logically that position would be the same in the converse situation." 3. It follows logically that position would be the same in the converse situation." 3. We are bound by the judgment of the Constitution Bench having regard to the unambiguous statement of the law that Section 11A or Section 11B will not govern any recoveries or refund consequent upon the adjustment under sub-rule (5) of Rule 9B. The Tribunal cannot be faulted for having held that Section 11B will not govern claims for refund when the refund made is in respect of the duty paid prior to, or consequent upon the provisional assessment and at a stage where the final assessment has not been made. 4. Learned Counsel for the Revenue submitted that Rule 9B sub-rule (5) was subsequently amended with effect from 25-6-1999 by the addition of a proviso. It is not the case of the Revenue that that amendment is retrospective in operation. We are here in this case concerned with a period anterior to the date of the amendment. 5. Counsel for the Revenue also submitted that there are doubts about the true import of the observations of the Constitution Bench at paragraph 95 in the case of Mafatlal (supra) and that having regard to the clear provisions of Section 11B which refers to claims for "refund of any duty of excise" without reference to such claim being made after the final assessment, that provision should be regarded as being applicable to claims for refund whether before or after the stage of provisional assessment. It was further submitted by Counsel that the Revenue has filed an appeal to the Honourable Supreme Court against a judgment of CEGAT, which had held that Section 11B of the Act would not be applicable to case of provisional assessment. The details of the appeal said to have been filed has not been furnished. 6. In any event, we are bound by the law laid down by the Apex Court, and that law as is evident from a reading of paragraph 95 of the judgment in the case of Mafatlal (supra) is that Section 11B of the Act will not apply to the claims for refund in respect of provisional assessments. 7. We, therefore, do not see any need to call for a question, the answer to which has already been provided by the Supreme Court.