Barney v. Keokuk was a United States Supreme Court case that dealt with the issue of whether a city could be held liable for damages caused by a defective bridge. The case arose when a man named Barney was injured while crossing a bridge in the city of Keokuk, Iowa. The bridge was owned by the city, and Barney argued that the city was liable for his injuries because the bridge was in a state of disrepair. The Supreme Court held that the city was not liable for Barney's injuries because the bridge was not in a state of disrepair when the city acquired it. The Court reasoned that the city had no duty to inspect the bridge and that it was not responsible for any defects that existed prior to its acquisition. The Court also noted that the city had taken reasonable steps to maintain the bridge and that it was not negligent in its maintenance. The Court's decision in Barney v. Keokuk established that a city cannot be held liable for damages caused by a defective bridge that it did not create or maintain. The Court's ruling also established that a city is not responsible for any defects that existed prior to its acquisition of the bridge. This ruling has been cited in numerous cases since then, and it has become an important precedent in determining the liability of cities for damages caused by defective bridges.

In the case of Barney v. Keokuk, the Supreme Court was asked to decide whether a city ordinance that prohibited steamboats from landing at certain docks in Keokuk, Iowa violated the commerce clause of the United States Constitution. The majority opinion held that it did not violate this clause and thus upheld the ordinance. However, Justice Field dissented on behalf of himself and two other justices. He argued that while states have some authority over their internal affairs, they do not have absolute power to regulate commerce within their boundaries as doing so would be contrary to Congress’s exclusive right under Article I Section 8 Clause 3 of the Constitution which grants them “the Power To regulate Commerce with foreign Nations, and among several States…” Thus he concluded that since Congress had not yet regulated navigation or trade along rivers such as those in Keokuk then any regulation by state governments should be considered unconstitutional interference with interstate commerce.