Smith v. Alabama was a United States Supreme Court case that dealt with the issue of due process. The case involved a man named William Smith who was convicted of murder in the state of Alabama. Smith argued that he had been denied due process of law because he had not been allowed to present evidence in his defense. The Supreme Court ruled in favor of Smith, finding that he had been denied due process of law. The Court held that the state of Alabama had violated Smith's right to due process by not allowing him to present evidence in his defense. The Court also held that the state had violated Smith's right to a fair trial by not allowing him to present evidence in his defense. The Court's ruling in Smith v. Alabama established that the state must provide a defendant with the opportunity to present evidence in his defense in order to ensure that he receives a fair trial. This ruling has been cited in numerous cases since then, and it has become an important part of the due process protections afforded to criminal defendants.

Justice Harlan wrote a dissenting opinion in the case of Smith v. Alabama, arguing that the conviction should be reversed due to an error in jury selection. He argued that African Americans were systematically excluded from juries and thus denied their right to equal protection under the law as guaranteed by the Fourteenth Amendment. This exclusion was based on race and not any other relevant factor such as criminal history or mental capacity, which made it unconstitutional according to Justice Harlan's interpretation of existing laws at that time. Furthermore, he argued that this practice had been going on for years without consequence and needed to be addressed immediately if justice was truly being served in courtrooms across America. In conclusion, Justice Harlan believed there had been a clear violation of constitutional rights during Smith’s trial and therefore his conviction should have been overturned regardless of whether or not he committed a crime because no one can receive fair treatment when they are deprived access to an impartial jury solely based on their skin color.