Trade parlance Theory :
Since the primary objective of the excise act is to raise revenue, resort should not be had, for purpose of classification to the scientific and technical meaning of the terms and expressions used therein, but to their popular meaning, that is to say, the meaning attached to that by those using the product.
The burden of proof that a product is classifiable under a particular tariff head is on the revenue and must be discharged by proving that it is so understood by the consumers of product in common parlance – CCE v. Vicco Laboratories 2005 (179) ELT 17 (SC 3 member bench).
Criteria for classifications are given in the Tariff. However, basic principle of classification, devised more than a century ago by justice pollok in Grenfell v. IRC (1876) 1 Ex D 242 continues. As per this principle, a word in statue should be construed in its popular sense and not in the strict or technical sense, ‘Popular sense’ means that which people conversant with the subject matter with which the statue is dealing would attribute to it.