In Parker v. Ellis, the petitioner, a Texas state prisoner serving a life sentence for murder, sought to challenge his conviction on constitutional grounds in federal court. He argued that he was denied due process because of an alleged coerced confession and inadequate legal representation during his trial. The U.S Supreme Court dismissed the case as moot since Parker had been paroled while his appeal was pending before the Court. The majority opinion held that once a convict is released from custody, even on parole, he loses standing to seek relief in federal courts through habeas corpus proceedings unless there are "collateral consequences" of his conviction which survive release from actual custody.

In the dissenting opinion for Parker v. Ellis, Justice Hugo Black argued that the court should have heard Ellis' appeal because he was denied his constitutional right to a fair trial. He believed that there were significant issues with how evidence was presented and handled in the original case, which could have influenced its outcome. Specifically, he pointed out that certain pieces of evidence were not properly authenticated before being admitted into court proceedings and this could potentially violate due process rights under the Fourteenth Amendment. Additionally, Justice Black expressed concern over whether or not Ellis had been adequately represented by counsel during his trial as required by Sixth Amendment protections. In essence, Justice Black's dissent focused on potential violations of constitutional rights within criminal trials and emphasized an individual’s right to a fair legal process regardless of their guilt or innocence.