Gregory killed a business associate, Burrows, because of paranoid delusions that persons acting through Burrows were trying to kill Gregory and his family. He was charged with murder and was committed to Atascadero State hospital as incompetent to stand trial. After his competency was restored, he pleaded guilty to second degree murder. A jury found him legally sane at the time of the offense. The trial court subsequently granted a habeas petition on the basis that the guilty plea was not knowing and intelligent because Gregory was not advised of, and could not appreciate, the possible defense (imperfect self-defense) he was waiving. Here, the appellate court reversed the ruling of the trial court. Since, as a matter of law, a claim of imperfect self-defense was not available to Gregory, whose defense was based on delusion, it follows that the lack of advice could not have rendered his plea unknowing or unintelligent. However, since the trial court did not rule on other possible grounds for relief, remand was required.