Minnesota v. Barber was a Supreme Court case that was decided in 1977. The case involved a Minnesota law that prohibited the sale of non-intoxicating beer to persons under the age of 21. The defendant, Robert Barber, was a 19-year-old who was charged with violating the law after he purchased a six-pack of beer from a liquor store. Barber argued that the law violated his right to equal protection under the Fourteenth Amendment. The Supreme Court agreed and held that the law was unconstitutional. The Court reasoned that the law was not narrowly tailored to serve a compelling state interest and that it was not rationally related to the state's interest in protecting minors from the dangers of alcohol. The Court also noted that the law was not necessary to protect minors from the dangers of alcohol because the state already had laws that prohibited the sale of alcohol to minors. The Court concluded that the law was an unconstitutional infringement on the right to equal protection and struck it down.

In the Supreme Court case of Minnesota v. Barber, Justice Brennan wrote a dissenting opinion in which he argued that the majority’s decision was too broad and could lead to potential abuses by law enforcement officials. He noted that while it is true that an individual has no right to privacy when they are in public places, this does not mean that police officers can search them without cause or suspicion. The Fourth Amendment protects individuals from unreasonable searches and seizures, regardless of where they are located at any given time. Furthermore, Justice Brennan argued that allowing such searches would be detrimental to civil liberties as it would give police officers unchecked power over citizens who may have done nothing wrong but simply happened to be present at a particular location when searched by authorities. In conclusion, Justice Brennan believed the majority’s ruling went too far and should have been more limited so as not to infringe upon individuals' constitutional rights under the Fourth Amendment.