I am representing an individual charged with murder in the first degree and it appears the death penalty will be sought. The evidence is overwhelming. I want to focus on the penalty phase. The client, who I think is mentally unbalanced, wants me to fight the guilt/innocence phase. What can I ethically do?

The question is very interesting, particularly in view of the recent U.S. Supreme Court case in McCoy v. Louisiana, U.S.-538 Supreme Court 1500 (2018). In McCoy, the Supreme Court reversed the conviction and indicated the defendant had a Sixth Amendment right to insist that his counsel refrain from admitting that the defendant committed the three murders during the guilt/innocence phase of the capital trial. The court made that ruling even though trial counsel believed that by admitting guilt, it gave the defendant his best chance to avoid the death penalty.