Davis v. Beason is a Supreme Court case from 1890 that dealt with the constitutionality of a law passed by the Idaho legislature that prohibited polygamists from voting or holding public office. The law was challenged by Davis, a Mormon who was denied the right to vote because of his religious beliefs. The Supreme Court ruled in favor of the Idaho legislature, finding that the law was constitutional. The Court held that the law was a valid exercise of the state's police power and that it did not violate the First Amendment's guarantee of religious freedom. The Court also noted that the law was not intended to target any particular religion, but rather to promote public morality. The decision in Davis v. Beason was an important one in the history of the Supreme Court, as it established the principle that the government can regulate certain activities in order to promote public morality. This principle has been used to uphold a variety of laws, including those prohibiting prostitution, gambling, and drug use.

In the dissenting opinion of Davis v. Beason, Justice Harlan argued that the majority’s decision to uphold an Idaho law prohibiting non-citizens from voting was unconstitutional and violated the Privileges or Immunities Clause of the Fourteenth Amendment. He reasoned that this clause protects citizens’ fundamental rights, including those related to political participation such as voting. Furthermore, he noted that while states have a right to regulate their elections in certain ways, they cannot deny any citizen their constitutional right to vote based on race or national origin. In conclusion, Justice Harlan believed that by upholding this law which denied non-citizens their right to vote without due process of law and equal protection under the laws it violated both clauses of the Fourteenth Amendment and should be overturned accordingly.