Panetti was found to be suffering from a "fragmented personality, delusions, and hallucinations" for which he had been hospitalized over 12 times and for which he had been prescribed high doses of powerful psychiatric drugs for schizophrenia.

Once these federal habeas proceedings had ended, the state trial judge, Steven Ables, set an execution date of February 5, 2004.

The state trial court responded by closing the case, ruling that Panetti did not show he was incompetent to be executed.

The Fifth Circuit affirmed the denial of Panetti's habeas petition,[4] and on January 4, 2007, the U.S. Supreme Court agreed to review the case.

The case was argued before the Supreme Court on April 17, 2007, with Texas Solicitor General Ted Cruz appearing for the state.

[5] On June 28, 2007, the last day of the term, the Supreme Court reversed and remanded by a vote of 5-4, with Justice Anthony Kennedy writing for the majority.

The Court therefore lacked jurisdiction to entertain it unless he could overcome the bar on "second or successive" habeas petitions imposed by the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA).

The Court ruled that Panetti's petition was not barred as "second or successive" because his Ford claim did not become ripe until his execution was imminent.

It rejected the State's contrary argument because of the perverse results it would have generated – inmates could be forced to litigate their competency to be executed before any signs of mental illness had set in.

Panetti was entitled to the procedural protections of Ford because he had made the required threshold showing; indeed, if he had not done so, why had the state trial court appointed the mental health experts to evaluate him?

Ford supplied the clearly established law by which to evaluate the Texas courts' treatment of Panetti's claim.

One expert opined that Panetti suffered from schizo-affective disorder, resulting in a genuine delusion regarding the reason for his execution.

Panetti's experts reminded the court that schizophrenia does not diminish a person's cognitive abilities, such that during short interactions the patient may appear lucid.

The Eighth Amendment forbids executing the insane because doing so offends human decency in that it serves neither the goal of retribution or deterrence.

"The potential for a prisoner's recognition of the severity of the offense and the objective of community vindication are called into question, however, if the prisoner's mental state is so distorted by a mental illness that his awareness of the crime and punishment has little or no relation to the understanding of those concepts shared by the community as a whole."

Both the Texas courts' procedural missteps and the Fifth Circuit's substantive definition of incompetence precluded consideration of this contention.