MA H4016

Creates new Chapter 233A establishing rules for admitting neuroscience evidence about "fight or flight" responses in criminal proceedings to address questions of liability, intent, and culpability

Defines "fight or flight response" as an involuntary physiological reaction that may temporarily overwhelm a person's capacity for reason, conscience control, and judgment during perceived threats

Allows defendants claiming self-defense to introduce neuroscience evidence showing they were cognitively incapable of avoiding physical combat or limiting force due to involuntary fight-or-flight responses

Shifts burden to prosecution to prove beyond reasonable doubt that defendant's actions exceeded what was necessary when credible neuroscience evidence of cognitive impairment is presented

Requires courts to provide jury instructions explaining how fight-or-flight responses may affect a defendant's ability to make conscious decisions, and how such evidence relates to self-defense requirements