In County of Cass v. Johnston, the Supreme Court of the United States was asked to decide whether a county in the state of Iowa had the authority to levy a tax on the property of a non-resident. The plaintiff, Johnston, was a non-resident of the county and owned property within its boundaries. The county had levied a tax on Johnston's property, and Johnston argued that the county did not have the authority to do so. The Supreme Court held that the county did have the authority to levy the tax. The Court reasoned that the state of Iowa had granted the county the power to levy taxes, and that the county had the right to tax the property of non-residents. The Court also noted that the tax was not discriminatory, as it was applied equally to all non-residents. In conclusion, the Supreme Court held that the county had the authority to levy a tax on the property of a non-resident, and that the tax was not discriminatory. The Court's decision affirmed the county's right to levy taxes on non-residents.

In the case of County of Cass v. Johnston, the Supreme Court was tasked with determining whether a county could be held liable for damages caused by its failure to repair a bridge that had been damaged in an accident. The majority opinion found that counties are not liable for such damages and thus dismissed the plaintiff's claim against them. However, Justice Field dissented from this ruling on two grounds: first, he argued that under common law principles counties should be held responsible for maintaining public roads and bridges; second, he noted that while there may have been no legal obligation to repair the bridge at issue here, it would still have been prudent to do so given its importance as a public thoroughfare. Ultimately then, Justice Field concluded that if any party is going to bear responsibility for failing to maintain or repair this particular bridge it should be Cass County itself rather than leaving innocent victims without recourse when they suffer harm due to negligence on behalf of local government entities.