All statements or invoices submitted to the city for work performed shall contain a sworn certification by the supervising architect or engineer, or other supervisory official if no supervisory architect or engineer is employed for the project, that work for which payment is claimed has been performed and that such work conforms to the plans and specifications for the project. No such statement or invoice shall be paid by the city without such certification. The execution of a sworn certificate, as herein provided, shall not constitute a defense or in any other manner affect any cause or causes of action which the city might otherwise have against the contractor for nonperformance of a public construction contract. (1985 Code § 7-326; amd. 2003 Code)