Iowa Code § 625A.13: Arguments in re constitutional test.

If the action challenges the legality, validity or constitutionality of a proposed constitutional amendment, the appellant shall file a written argument with the supreme court within ten days after the filing of the abstract and appellee shall file an argument within ten days thereafter, and appellant shall then file a reply within three days. The cause shall then be submitted to the supreme court in regular or special en banc session as soon thereafter as the chief justice may order.