In South Carolina State Highway Department v. Barnwell Brothers Inc., the Supreme Court rules that states have the authority to determine local shipping regulations provided they apply regulations equally to interstate and intrastate highways. The Barnwell Brothers shipping company sues to enjoin the enforcement of a South Carolina law barring trucks that weigh over 20,000 pounds and measure over 90 inches wide from using state highways. Barnwell contends that 90 percent of shipping trucks are 96 inches wide and only four states enforce a 20,000-pound maximum. The Court’s decision effectively shows that states have the power to regulate commerce-related issues in the absence of congressional legislation, when state legislation does not conflict with federal regulations or with interstate commerce.