TABAI JSC (Delivering the Lead Judgment): The plaintiff was therespondent at the court below and the appellant herein. The defendant was the appellant at the court below and the respondent herein. They would, in this judgment be simply referred to as the appellant and the respondent respectively. Sometime in the year 1987, the parties entered into a contractunder which the appellant was to construct for the respondent a soap and detergent factory as well as office building at the Kudenda Industrial Layout, Kaduna at the contract sum of N3,854,938.10 (three million, eight hundred and fifty-four thousand, nine hundred and thirty-eight naira, ten kobo). It was part of the agreement that the respondent would pay to the appellant such part of the contract sum raised in a certificate of payment issued by architects appointed by the respondent. It was also part of the agreement that the sum stated in any certificate of payment fell due and payable within 21 days of the issuance of the cert…