Customs Act (52 of 1962) , S.151A, S.14— Customs Valuation (Determination of Price of Imported Goods) Rules (1988) , R.5— Assessment of value of imported goods - Circular dated 14th August, 1991 - Issued by Central Board of Excise and Customs - Providing that demurrage did not form part of assessable value of goods imported - Binding on revenue - Demand based on assessable value inclusive of demurrage - Cannot be sustained as long as circular remained operative - Principle of promissory estoppel - Cannot be held to be not applicable on ground that assessee had not acted on basis of circular. Evidence Act (1 of 1872) , S.115— Per Court :- Where the circular dated 14th Aug., 1991 issued by Central Board of Excise and Customs provided that demurrage did not form part of assessable value of goods imported, it would be binding on Revenue and therefore demand by customs authorities based on assessable value inclusive of demurrage cannot be sustained.(Para 14 23) Per Ruma Pal, J. :- Although a circular by Central Board of Excise and Customs is not binding on a Court or an assessee, it is not open to the Revenue to raise the contention that is contrary to a binding circular by the Board. When a circular remains in operation, the Revenue is bound by it and cannot be allowed to plead that it is not val....