Under which constitutional principle was the Iowa truck ban likely found to be unconstitutional?

The ban on trucks in Iowa is likely found to be unconstitutional under the dormant commerce clause, which is a legal doctrine derived from the Commerce Clause in the U.S. Constitution. This principle prohibits states from enacting laws that excessively burden interstate commerce.

The dormant commerce clause aims to ensure that states do not create barriers to trade between states, promoting a free and open market across the country. In this context, if Iowa's truck ban restricts out-of-state trucks from entering or operating within its borders without a valid justification related to health, safety, or welfare, it could be deemed an undue burden on interstate commerce. Courts typically evaluate such regulations to ensure they do not discriminate against out-of-state interests or create a patchwork of state laws that could disrupt the national market.

The other options represent constitutional principles that focus on different aspects of law. The free exercise clause pertains to religious freedoms, the sovereignty principle relates to the authority of states, and the privileges and immunities clause protects citizens' rights in different states. While these principles are crucial in their contexts, they do not directly address the issues surrounding the regulation of interstate commerce as the dormant commerce clause does. Therefore, it reinforces why the dormant commerce clause is the appropriate basis for finding the Iowa truck ban