The Dinsmore v. Southern Express Company and Georgia Railroad Commission case in 1901 revolved around the issue of interstate commerce regulation. The plaintiff, Dinsmore, was a shareholder in the Southern Express Company which operated across several states. He filed suit against both the company and the Georgia Railroad Commission after they agreed to reduce shipping rates within Georgia following pressure from local businesses and farmers who found previous rates too high. Dinsmore argued that this agreement violated federal law as it interfered with interstate commerce by creating different rate structures for intrastate versus interstate shipments. The Supreme Court ruled in favor of Southern Express Company and Georgia Railroad Commission, stating that while Congress had power over interstate commerce, individual states also retained their authority to regulate aspects of trade occurring solely within their borders unless such regulations directly conflicted with federal laws or impeded on national interests. This decision upheld state regulatory powers over intrastate business activities even when those businesses were part of larger operations spanning multiple states.

The dissenting opinion in the case of Dinsmore v. Southern Express Company and Georgia Railroad Commission argued that the state's regulation of interstate commerce was not unconstitutional, as it did not conflict with federal law or impede its operation. The dissenters believed that states should retain their power to regulate local matters unless Congress explicitly preempts them from doing so. They contended that a state could impose reasonable regulations on businesses operating within its borders, even if those businesses were engaged in interstate commerce, provided such regulations did not contradict any federal laws or interfere with Congress' ability to regulate interstate commerce. Therefore, they disagreed with the majority's decision which held that Georgia’s requirement for express companies to obtain a license before conducting business was an unlawful interference with interstate commerce.