Iowa Code § 692A.127: Limitations on political subdivisions.

A political subdivision of the state shall not adopt any motion, resolution, or ordinance regulating the residency location of a sex offender or any motion, resolution, or ordinance regulating the exclusion of a sex offender from certain real property. A motion, resolution, or ordinance adopted by a political subdivision of the state in violation of this section is void and unenforceable and any enforcement activity conducted in violation of this section is void.