In Allen v. United States (1893), the U.S Supreme Court ruled on a case involving an individual who had been convicted of murder in Arizona, which was then a federal territory. The defendant, Allen, argued that his conviction should be overturned because he was not allowed to testify at his own trial due to rules barring defendants from testifying in their defense. However, the court upheld his conviction stating that while it is true that Congress passed a law allowing defendants to testify on their behalf after Allen's trial took place; this law could not be applied retroactively and therefore did not apply to him. Furthermore, they stated there were no constitutional issues with preventing someone accused of crime from testifying at their own trial as it does not violate any specific rights guaranteed by the Constitution.

In the dissenting opinion for Allen v. United States, Justice Brewer argued that the jury instruction given by the trial court was incorrect and prejudicial to the defendant's rights. He contended that it is not enough for a judge to simply instruct jurors on reasonable doubt; they must also be told what constitutes such doubt. In this case, he believed that jurors were led to believe they could convict if there was any possibility of guilt, rather than being certain beyond a reasonable doubt - an error which undermined their duty as fact-finders in criminal cases. Furthermore, he disagreed with majority’s view about harmless errors stating every error in instructions upon matters of law is presumed to have been followed by injury unless contrary appears affirmatively from whole record. Thus, according to him even though evidence against accused might seem overwhelming yet erroneous instructions are harmful and cannot be considered harmless.