The U.S. Supreme Court case David Bobby, Warden v. Harry Mitts in 2010 revolved around the issue of jury instructions during the penalty phase of a capital murder trial. The defendant, Harry Mitts, was convicted for two counts of aggravated murder and attempted murder in Ohio state court. During his sentencing hearing, the judge instructed jurors that they must unanimously find beyond reasonable doubt that mitigating factors outweighed aggravating circumstances before recommending life imprisonment over death sentence - an instruction which Mitts argued violated his Eighth Amendment rights against cruel and unusual punishment by creating a presumption in favor of death penalty when there's no unanimous agreement on mitigation evidence. Mitts sought federal habeas relief but both district court and Sixth Circuit granted it based on their interpretation that such jury instructions were unconstitutional according to previous rulings (Mills v Maryland & McKoy v North Carolina). However, upon reaching Supreme Court level, justices reversed these decisions stating those precedents didn't apply as they dealt with cases where juries were precluded from considering any non-unanimous mitigation findings at all whereas here jurors could consider all presented mitigations regardless of unanimity or lack thereof.

In the dissenting opinion for David Bobby, Warden v. Harry Mitts, Justice Sotomayor argued that the jury instructions given in Mitts' trial were unconstitutional and could have led to a death sentence based on an incorrect standard of proof. She contended that the jurors might have understood from these instructions that they had to find beyond a reasonable doubt not only each individual mitigating factor but also that those factors outweighed aggravating circumstances before they could consider imposing a life sentence instead of death. This interpretation would be contrary to previous Supreme Court rulings which held juries should not be precluded from considering any relevant mitigating evidence or required to find such evidence beyond a reasonable doubt. Furthermore, she disagreed with the majority's view that this issue was procedurally defaulted because it was raised too late in appeals; she believed there were valid reasons why it wasn't raised earlier and thus procedural default shouldn't apply.