Iowa Code § 20.28

A provision of the Code which is inconsistent with any term or condition of a collective bargaining agreement which is made final under this chapter shall supersede the term or condition of the collective bargaining agreement unless otherwise provided by the general assembly. A provision of a proposed collective bargaining agreement negotiated according to this chapter which conflicts with the Code shall not become a provision of the final collective bargaining agreement until the general assembly has amended the Code to remove the conflict.