A working guide to mental state issues in criminal cases, organized by the order in which they arise. Part one separates competency from insanity and explains why conflating them is the field's most common error. Part two covers the competency standard, the duty to inquire, burdens, and the special rules for pleading and self-representation. Part three covers restoration, its constitutional time limit, and the involuntary medication framework. Part four covers the insanity tests, the burden, and what a successful verdict actually produces. Part five covers diminished capacity. Part six covers intellectual disability and competency to be executed. Part seven covers experts and funding. Part eight covers diversion, mental health courts, and the systemic failures counsel has to work around.