Why did the Supreme Court reject the conviction in Brown v. Mississippi?

In Brown v. Mississippi (1936), the Supreme Court invalidated a state criminal conviction because it was based on a coerced confession.1

It is a common misconception to attribute this ruling directly to the Fifth Amendment, as the Bill of Rights originally applied only to the federal government and not to state law-enforcement practices. Instead, the Court’s decision relied on the due process clause of the Fourteenth Amendment. By doing so, the Court established that state-sanctioned physical brutality to extract confessions violated the fundamental principles of liberty and justice required by the Constitution. This landmark ruling marked a critical step in the process of selective incorporation, through which the Supreme Court began applying federal constitutional protections to state actions.12