Arizona Supreme Court: Habit - character can show impulsivity to support crime mental state (mens rea), but evidence of brain injury cannot be used to support that purpose. STATE v. MALONE, SUPREME COURT OF THE STATE OF ARIZONA No. CR-18-0431-PR Filed July 17, 2019
There are many paths in the brain, and injury can occur in some areas and not others.  Testimony was offered to the effect that neuropsychological assessment test result was “consistent with significant and permanent diffuse brain damage,” meaning Malone was “more likely to have a character trait for impulsivity.” In addition, no MRI scan or like evidence to bolster his assessment that Malone had brain damage [related to impulsivity]
The testimony was ruled inadmissible.  If the damage was tied to a brain scan showing that damage was to an impulsivity related area, the threshold might have been met, but no physiological connective showing was made.
Further, behavioral tendencies is equivalent to "diminished capacity evidence" and may be admitted to challenge the mens rea of premeditation. PATENTAX