The Gist: The Missouri Constitution only allowed men to vote. A woman challenged this law, arguing it was a violation of the U.S. Constitution under the Privileges and Immunities Clause of the 14th Amendment. The Supreme Court held that the protections of the 14th amendment did not include the right to vote.
The Details: Virginia Minor was a leader of the women's suffrage movement whose attempt to vote was denied by a state registrar on the grounds that it violated the Missouri Constitution, which only allowed men to vote. Minor brought this lawsuit, alleging the Missouri Constitution violated the 14th Amendment of the U.S. Constitution. The 14th amendment states:
No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
Specifically, Minor argued that the law abridged her privilege (the right to vote) as a U.S. citizen. Following the same controversial reasoning in the Slaughterhouse Cases, the court narrowly interpreted the 14th amendment as only protecting citizenship rights of former slaves and not meant to expand to change other state laws. It also stated that the second clause of the 14th amendment's specific reference to only male voters (the clause penalizes states for denying the right to vote to "male inhabitants") clearly showed that the 14th amendment was not intended to protect the rights of other classes of voters. Ruling that voting was not one of the privileges or immunities of U.S. citizens, the Supreme Court paved way for states to continue denying the right to vote to women
In 1920, Congress passed the 19th amendment, which prohibits denying a U.S. citizen the right to vote based on sex. This effectively overruled the holding in Minor.