Mississippi Supreme Court Denies Appeal from Defendant Claiming Trial Counsel Ignored Neuroscientific Evidence

Above: Jason Lee Keller. (Sun Herald)

On December 10, 2020, the Supreme Court of Mississippi affirmed Jason Lee Keller’s capital murder conviction and denied his appeal, rejecting his claims that his counsel was ineffective for failing to present additional mitigating evidence about his psychological functioning.

In 2007, when Keller was 27 years old, he robbed and murdered a woman in a convenience store. He was convicted of capital murder and sentenced to death. Keller petitioned for and was granted post-conviction relief in 2017 by the Supreme Court of Mississippi. Consequently, the trial court conducted an evidentiary hearing, at which Keller argued that his trial counsel was ineffective because, among other reasons, they did not present mitigating neuroscientific evidence. The trial court denied Keller’s request for a new sentencing hearing before a new jury. Keller appealed this decision.

Keller’s mental health and psychological functioning were addressed at his trial. Two doctors testified that Keller fell within the “mildly impaired range of neuropsychological functioning” which affected his emotional processing, problem solving, and judgement. One doctor also stated at trial that Keller may have PTSD from childhood burns and opined that “Keller’s drug abuse, ADHD, PTSD, low-average IQ, and brain dysfunction were all working together when Keller murdered the victim.”

Keller claimed that trial counsel should have presented additional mitigating evidence of family neglect, his placement in special education programs, and further testing of his psychological functioning. The trial court found that Keller’s counsel followed through with each of these concerns and that it was “within trial counsel’s ability to choose a mitigation strategy she thought would be most effective.”

The Mississippi Supreme Court affirmed the trial court’s decision. “Based on the strong presumption that trial counsel provided adequate assistance and on the highly deferential standard of review, the trial judge did not clearly err by finding that trial counsel provided adequate assistance.”

Citation: Keller v. State, 306 So.3d 706

Key words: Mississippi, neuroscience, death sentence

This post is the 76th post as part of an ongoing Center for Law, Brain & Behavior (CLBB) series tracking the latest developments in law and neuroscience cases. To see previous posts about recent cases, see the full case archive on the CLBB website. To see updates on legal scholarship, see the Neurolaw News, hosted by the MacArthur Foundation Research Network on Law and Neuroscience. This project is made possible through support of the Dana Foundation.




at Mass General Hospital, Harvard Medical School

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Center for Law, Brain & Behavior

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at Mass General Hospital, Harvard Medical School

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