Brain injury may not excuse a crime, but increasingly it has been used in courtrooms to shape punishment. This month, October 2026, Alberto Sierra’s lawyers showed penalty-phase jurors a 3D-printed model of frontal-lobe damage from childhood car crash, in Miani-Dade. (Their expert, though, did not say the injury caused the triple murder.) In Raleigh, Austin Thompson’s brain injury didn’t prevent five life-without-parole terms in February. However, in Indiana, Jeffrey Weisheit is seeking brain scans to support clemency before his November execution date.

The CDC has reported that almost half (46%) of incarcerated adults and about 1 in 3 detained juveniles have a TBI history his. While NIH-indexed studies find only a “modest causal link” between TBI and later convictions, it’s notable that less than 2 percent of the general public has a TBI history. It is uncertain, though, to what side and to what level the cause-and-effect aligns. A small 2023 PubMed-available study of 31 TBI patients found moral decision-making “not uniformly impaired”; lesion location and age at injury matter more.

The conclusion seems to be that brain injury buys mercy, not acquittal.