## Facts

- Robert Bradley Joseph was charged with first-degree murder for fatally shooting Scott Light after a confrontation at Light’s driveway following an evening of drinking and interpersonal conflict.
- Earlier that night, Joseph fired shots from his porch as Jessica Martin and Duane Lucas left his home; no one was injured.
- Joseph later searched for Martin, encountered her boyfriend Richard Hackney, and went with him to Light’s home, where Light had last been seen with Martin and Lucas.
- Joseph followed Light’s vehicle to Light’s driveway, questioned him about Martin’s whereabouts, and an argument ensued.
- Light opened Joseph’s truck door and slapped Joseph’s head; Joseph then retrieved a gun from the truck and shot Light.
- Joseph had a prior traumatic brain injury affecting the left frontal area; defense experts opined the injury caused cognitive and impulse-control deficits relevant to intent formation.
- At trial, the defense proffered psychiatric/neuropsychological expert testimony to support a diminished-capacity theory; the trial court heard the proffer in camera, found it insufficient, excluded it, and declined a diminished-capacity instruction.
- The jury convicted Joseph of first-degree murder with mercy, and he appealed.

## Issues

1. Whether West Virginia law permits a defendant to introduce expert evidence of mental disease or defect short of insanity to show inability to form a mental state that is an element of the charged offense (diminished capacity).
2. Whether the trial court erred by excluding Joseph’s proffered expert testimony as insufficient, thereby preventing the jury from considering diminished capacity as it related to mens rea.

## Decision

- The Supreme Court of Appeals of West Virginia held that diminished capacity is recognized in West Virginia as a means to negate an element of mens rea through expert testimony about mental disease or defect.
- The court held Joseph’s proffered expert testimony was sufficient to create a jury question on whether he could form the specific intent required for first- or second-degree murder.
- The court concluded the trial court improperly withheld relevant, reliable expert evidence and invaded the jury’s role in weighing its significance.
- The conviction was reversed, and the case was remanded for a new trial.

## Legal Principles

- A defendant may introduce expert testimony regarding a mental disease or defect (short of legal insanity) that rendered the defendant incapable, at the time of the offense, of forming a mental state that is an element of the crime charged.
- Diminished capacity functions as mens rea negation for specific-intent elements (e.g., premeditation, deliberation, malice), not as an independent excuse or partial-responsibility doctrine.
- The prosecution must prove every element of the offense beyond a reasonable doubt; relevant evidence that tends to negate the required mental state is for the jury to consider.
- Trial courts may screen proffered expert testimony for relevance and reliability, but credibility, weight, and competing factual inferences about mental state are for the jury.
- Exclusion of competent expert evidence bearing directly on intent is not harmless when it could affect the degree of homicide or the verdict.

## Conclusion

West Virginia recognizes diminished capacity as an evidentiary doctrine permitting reliable expert mental-health testimony to negate a charged offense’s required mental state, and a trial court may not exclude such evidence merely by deciding its persuasiveness; because Joseph’s expert proffer supported a jury question on intent, his first-degree murder conviction was reversed and the case remanded for a new trial.


State v. Joseph, 590 S.E.2d 718 (W. Va. 2003)