West v. Aurora City was a United States Supreme Court case that was decided in 1867. The case involved a dispute between the City of Aurora, Illinois and a local resident, John West. West had been arrested and fined for violating a city ordinance that prohibited the sale of liquor within the city limits. West argued that the ordinance was unconstitutional because it violated his right to due process of law. The Supreme Court agreed with West and held that the ordinance was unconstitutional. The Court reasoned that the ordinance was too vague and did not provide sufficient notice to citizens of what conduct was prohibited. The Court also held that the ordinance was overly broad and did not provide for any exceptions or exemptions. The decision in West v. Aurora City was significant because it established the principle that local governments must provide citizens with clear and specific laws that are not overly broad or vague. This decision has been cited in numerous subsequent cases involving the constitutionality of local ordinances.

In West v. Aurora City, the Supreme Court was tasked with determining whether a city ordinance that prohibited certain types of businesses from operating within its limits violated the Fourteenth Amendment's Equal Protection Clause. The majority opinion held that it did not, reasoning that cities have broad authority to regulate their own affairs and pass laws in order to promote public health and safety. However, Justice Field dissented from this decision on the grounds that such an ordinance constituted class legislation which discriminated against certain individuals based solely on their occupation or profession without any rational basis for doing so. He argued that while states may be able to exercise some control over what kinds of businesses can operate within their borders, they must do so in a manner consistent with constitutional protections like equal protection under law; otherwise they are violating fundamental rights guaranteed by the Constitution.