In the case of Edward Harold Schad, Jr. v. Arizona (1990), the U.S Supreme Court upheld a murder conviction and death sentence for Edward Harold Schad in a 5-4 decision. The central issue was whether or not it violated due process to instruct jurors that they could convict on first-degree murder if they found either premeditation or felony-murder (murder committed during another crime) without agreeing on which one occurred. The majority opinion held that this did not violate due process as long as each juror was convinced beyond reasonable doubt that defendant was guilty of first-degree murder under some theory presented by prosecution - even if there wasn't unanimous agreement about what exactly happened.

In the dissenting opinion for Edward Harold Schad, Jr. v. Arizona, Justice Blackmun argued that the jury instruction given in this case was constitutionally inadequate because it allowed jurors to convict without unanimously agreeing on whether Schad committed premeditated murder or felony murder. He believed that these are distinct crimes with different elements and moral culpability, not merely different means of committing a single offense as majority suggested. Therefore, he contended that due process requires unanimity on one or the other crime before conviction can occur. Furthermore, he criticized the Court's reliance on historical practices instead of focusing more directly on modern standards and principles of justice which require greater precision in criminal law than what was acceptable in past centuries.