In the case of Joe Mario Trevino v. Texas, 1991, Trevino was convicted for capital murder and sentenced to death in a Texas court. The main issue under consideration by the Supreme Court was whether or not it was constitutional for a jury to be instructed that they could consider mitigating evidence only if all jurors agreed on its existence and relevance. This instruction had been given during the penalty phase of Trevino's trial. The defense argued that this violated his Eighth Amendment rights against cruel and unusual punishment as well as his Fourteenth Amendment due process rights because it potentially prevented individual jurors from considering mitigating factors which might lead them to vote against imposing the death penalty. However, the Supreme Court upheld Trevino's conviction and sentence stating that there is no constitutional requirement for juries to agree unanimously on specific mitigating circumstances before considering them in their sentencing deliberations.

The dissenting opinion in the case of Joe Mario Trevino v. Texas argued that the majority's decision was inconsistent with previous rulings and failed to adequately consider whether Trevino had been given a fair opportunity to present his claims of ineffective counsel. The dissent pointed out that under existing precedent, defendants were allowed to raise such claims even if they hadn't done so at trial or on direct appeal, as long as state procedural rules didn't provide them with a meaningful chance to do so earlier. In this case, however, the majority held that because Trevino could have theoretically raised his claim during an initial post-conviction review process (even though he wasn't represented by counsel at this stage), he was barred from raising it later on federal habeas corpus review. The dissent criticized this reasoning as overly formalistic and disconnected from practical realities faced by defendants like Trevino who lacked legal representation during critical stages of their cases.