Judgment

Bharucha, J.-This appeal has been referred to a Constitution Bench for the reason that there are two conflicting three Judge Bench deci­sions of this Court on the point at issue.

2. Briefly stated, the facts are : The assessee-respondent manufac­tures NES yarn. It had filed classification lists with the Excise authorities, the appellants, which had been approved under the provi­sions of Rule 173B of the Central Excise Rules, 1944. The approval classified the NES yarn under old Tariff Item 19-I(2)(a)(2)(e). On 28th September, 1977, a notice was issued by the Excise authorities to the assessee to re-open the assessment for the period February, 1977 to May, 1977. The reason for so doing was that the NES yarn ought to have been correctly classified under old Tariff Item 19-I(2)(F). A demand for differential duty was made. A second show cause notice was issued by the Excise authorities to the assessee on 18th November, 1977 for the period 1st June, 1977 to 17th June, 1977. The assess­ment for this period was sought to be re-opened for the same reason. Again, a demand for differential duty was made. These show cause notices were amended by corrigenda dated 28th February, 1