San Antonio v. Mehaffy was a United States Supreme Court case that addressed the issue of whether a city could be held liable for damages caused by a defective bridge. The case arose when a man named Mehaffy was injured while crossing a bridge in San Antonio, Texas. The bridge was owned by the city and had been built by a private contractor. Mehaffy sued the city for damages, claiming that the bridge was defective and that the city was negligent in its maintenance. The Supreme Court held that the city could be held liable for damages caused by the defective bridge. The Court reasoned that the city had a duty to maintain the bridge in a safe condition and that it had breached that duty by failing to do so. The Court also held that the city was liable for the contractor's negligence in building the bridge, as the city had a duty to ensure that the bridge was built in a safe manner. The Court's decision established that cities can be held liable for damages caused by defective bridges and other public works. This decision has been cited in numerous cases since then, and it has been used to establish the principle that cities have a duty to maintain public works in a safe condition.

Justice Field delivered the dissenting opinion in San Antonio v. Mehaffy, arguing that the majority had erred in its interpretation of a Texas statute concerning municipal debt. He argued that under the plain language of the statute, it was clear that any bonds issued by a municipality were to be paid out of general taxes and not from special assessments levied on property owners within city limits. This interpretation was supported by both prior case law and legislative intent as expressed through other statutes passed at around the same time as this one. Furthermore, Justice Field noted that if his interpretation were adopted then cities would have greater financial flexibility when issuing bonds for public works projects since they could rely on general taxation rather than having to impose additional burdensome levies upon their citizens.