As per case facts, M/s Bilag Industries P. Limited (BIL) sold its manufactured products to Aventis CropScience (India) Ltd., both being subsidiaries of AgrEvo SA. The revenue department treated this ... as a sale between "related persons" under the Central Excise Act and sought to assess duty based on the end-customer price, leading to a differential duty demand. The CESTAT upheld this, finding the transactions mutually beneficial. The question arose whether BIL and Aventis CropScience (India) Ltd. qualified as "related persons" under Section 4(4)(c) of the Central Excise Act, 1944, requiring mutual interest in each other's businesses. Finally, the Supreme Court ruled that while a common holding company existed, there was no evidence of mutual interest of BIL in the buyer's business or vice-versa, nor was there proof of depressed pricing. Therefore, the revenue's decision to treat them as related persons was erroneous, and the appeals were allowed.