Section 2(4)(a) in Central Excise Laws (Amendment and Validation) Act, 1982
(a)all duties of excise levied, assessed or collected with respect to any goods under the Central Excise Act or the said rules or any Central law shall be deemed to be, and shall be deemed always to have been validly levied, assessed or collected as if the foregoing provisions of this section had been in force at all material times;