The Iowa legislature drafts law, which if passed by that body and signed by the governor, then become state law. Occasionally, the legislature will pass a law and in the course of a prosecution or other litigation, it will be declared unconstitutional by a court.
When someone is charged with a crime, one question that is not always obvious is "What crime are the charged with?" Take, for instance, the recent arrest of the Mayor of Fairfax, Virginia. He was involved with a transaction at a hotel where he gave methamphetamine to a police officer. In most cases in Iowa City, such behavior would likely bring a charge of possession and very possibly a more severe charge.