160 U.S. 469, 16 S. Ct. 353, 40 L. Ed. 499 (1895)
Dennis Davis was indicted for the crime of having, on the 18th day of September, 1894, at the Creek Nation, in the Indian Territory, within the Western District of Arkansas, feloniously, wilfully, and of his malice aforethought, killed and murdered one Sol Blackwell.1
He was found guilty of the charge in the indictment. A motion for a new trial having been overruled, and the court having adjudged that the accused was guilty of the crime of murder, as charged, he was sentenced to suffer the penalty of death by hanging.2
At the trial below the government introduced evidence which, if alone considered, made it the duty of the jury to return a verdict of guilty of the crime charged.3 But there was evidence tending to show that at the time of the killing the accused, by reason of unsoundness or weakness of mind, was not criminally responsible for his acts.4
In addition to the evidence of a practicing physician of many years standing, and who, for the time, was physician at the jail in which the accused was confined previous to his trial, other witnesses testified that they had been intimately acquainted with the defendant for several years, lived near him, and had been frequently with him, knew his mental condition, and that he was weak-minded, and regarded by his neighbors and people as being what they called half crazy. Other witnesses who had known the defendant for ten to twenty years, witnesses who had worked with him and had been thrown in constant contact with him, said he had always been called half crazy, weak-minded; and in the opinion of the witnesses defendant was not of sound mind.5
Whether, in a murder prosecution where the fact of killing is established, the jury may properly return a verdict of guilty if, upon the whole evidence, they have a reasonable doubt whether at the time of the killing the accused was mentally competent to distinguish between right and wrong or to understand the nature of the act he was committing?6
In a criminal prosecution the government bears the burden throughout the trial of proving beyond a reasonable doubt every fact necessary to constitute the crime charged. This includes that the accused possessed sufficient mental capacity to distinguish right from wrong and to understand the nature of the act. The presumption of sanity supplies an initial inference but remains rebuttable. It cannot authorize conviction when evidence from any source creates a reasonable doubt on the issue of sanity.7
No. At the trial below the government introduced evidence which, if alone considered, made it the duty of the jury to return a verdict of guilty of the crime charged.8 But there was evidence tending to show that at the time of the killing the accused, by reason of unsoundness or weakness of mind, was not criminally responsible for his acts.
The trial court nevertheless instructed the jury that the defense of insanity could not avail unless established to the reasonable satisfaction of the jury. It also instructed that the presumption of sanity would support a guilty verdict even if the evidence on mental capacity remained in equipoise.9
This instruction permitted conviction despite the existence of reasonable doubt on an essential element of the crime.10
The judgment of conviction and sentence of death must be reversed. The jury was permitted to return a guilty verdict even though the whole evidence left reasonable doubt whether Davis was mentally competent to commit the crime charged.11