What does the Dormant Commerce Clause restrict?

The Dormant Commerce Clause refers to the implicit restriction that prohibits states from enacting legislation that discriminates against or excessively burdens interstate commerce. It asserts that while the U.S. Constitution grants Congress the power to regulate interstate commerce, it also limits the states' abilities to interfere with that commerce.

The correct answer focuses on the notion that states cannot pass laws that create significant obstacles to trade across state lines. The rationale behind this principle is to maintain a national economic market free from state-imposed barriers. This ensures that commerce can flow freely among states without facing discriminatory or undue burdens, which could lead to economic fragmentation and inefficiencies.

In this context, other options do not accurately describe the reach or purpose of the Dormant Commerce Clause. For example, while states cannot impose tariffs, the focus on tariffs specifically relates more to the powers reserved for Congress rather than the broader implications of the Dormant Commerce Clause. The third option regarding trade with foreign nations actually pertains to the powers of Congress, as only the federal government can regulate foreign commerce. Lastly, the assertion that the Dormant Commerce Clause has no effect on state laws misrepresents its fundamental purpose, which is to serve as a restriction on state regulation that affects interstate trade.