Carson v. Ober was a United States Supreme Court case that dealt with the issue of whether a state could constitutionally require a person to pay a fee in order to vote in a state election. The case was brought by a group of African-American citizens in the state of Mississippi who were denied the right to vote in a state election because they had not paid a fee. The Supreme Court held that the state's requirement of a fee to vote was unconstitutional. The Court reasoned that the fee requirement violated the Equal Protection Clause of the Fourteenth Amendment, which prohibits states from denying citizens the right to vote on the basis of race or color. The Court also held that the fee requirement was an unconstitutional burden on the right to vote, as it effectively prevented many citizens from exercising their right to vote. The Court concluded that the fee requirement was an unconstitutional infringement on the right to vote and struck it down.

In Carson v. Ober, the Supreme Court was asked to decide whether a state could constitutionally require that all marriages be performed by clergymen of some religious denomination. The majority opinion held that such a requirement did not violate the Fourteenth Amendment's Equal Protection Clause because it applied equally to all religions and thus did not discriminate against any particular religion or group of people. Justice Field dissented from this decision, arguing that while the law may have been intended to apply equally across religions, in practice it would still result in discrimination against those who do not adhere to any organized religion or whose beliefs are outside of mainstream Christianity. He argued further that requiring marriage ceremonies conducted by clergymen violated both freedom of conscience and freedom of contract as guaranteed under the Constitution since individuals should be able to choose their own form for solemnizing their union without interference from government authorities.