Insanity Defense
The insanity defense asserts that defendant, due to mental disease or defect, lacked capacity to understand wrongfulness of conduct or conform behavior to law. California uses McNaughten test.
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Exam Tip
California uses M'NAGHTEN: know (1) nature/quality OR (2) wrongfulness? NO irresistible impulse or MPC in CA.
What is the Insanity Defense?
Insanity absolves criminal liability based on mental illness at time of offense. Admits act but denies responsibility.
Tests for Insanity
| Test | Standard |
|---|---|
| M'Naghten | Didn't know nature/quality OR wrongfulness |
| Irresistible Impulse | Couldn't control despite knowing wrong |
| MPC/ALI | Lacked substantial capacity |
| Durham | "Product of" mental disease |
California (M'Naghten)
PC Section 25(b):
- Cognitive Prong: Know nature/quality?
- Moral Prong: Know it was wrong?
California Specific Rules
| Rule | Application |
|---|---|
| No Diminished Capacity | Abolished |
| Bifurcated Trial | Guilt phase, then sanity |
| Defendant's Burden | Preponderance of evidence |