Tilley v. County of Cook was a United States Supreme Court case that addressed the issue of whether a county could be held liable for damages caused by a defective bridge. The plaintiff, Tilley, was injured when his horse and wagon fell through a bridge that had been built by the county. Tilley sued the county for damages, arguing that the county was liable for the defective bridge. The Supreme Court held that the county was liable for the damages caused by the defective bridge. The Court reasoned that the county had a duty to maintain the bridge in a safe condition, and that the county had failed to do so. The Court also noted that the county had received money from the state to build and maintain the bridge, and that the county had a duty to use that money to ensure the bridge was safe. The Court concluded that the county was liable for the damages caused by the defective bridge, and that Tilley was entitled to recover damages from the county. This case established that counties can be held liable for damages caused by defective bridges that they have built and maintained.

In the case of Tilley v. County of Cook, Justice Field delivered a dissenting opinion in which he argued that the majority opinion was wrongfully decided and should be reversed. He asserted that under Illinois law, when an individual is appointed to a public office by virtue of their election, they are entitled to receive compensation for services rendered during their tenure regardless if it has been provided for or not. In this particular case, Tilley had been elected as county treasurer but did not receive any salary despite performing all duties associated with his position. Therefore, Justice Field concluded that since there was no express provision denying him compensation in either state statute or local ordinance and because he had performed all necessary functions required by law while serving as county treasurer without receiving pay from the county board; then he should have received some form of remuneration for his service even though it wasn't explicitly stated anywhere else.