Depends on the applicable test:
1. M'Naghten Rule: Under this rule, a defendant is entitled to acquittal if: (1) a disease of the mind; (2) caused a defect of reason; (3) such that the defendant lacked the ability at the time of his actions to either know the wrongfulness of his actions or understand the nature and quality of his actions.
>>> Delusions, belief that one's actions are morally right, or loss of control because of mental illness are NOT defenses unless this test is met.
2. Irresistible Impulse Test: Under this test, a defendant is entitled to acquittal only if, because of a mental illness, he was unable to control his actions or conform his conduct to the law.
3. Durham (or New Hampshire) Test: Under this test, a defendant is entitled to acquittal if the crime was the product of his mental illness (i.e., crime would not have been committed but for the disease). The Durham test is broader than either the M'Naghten test or the irresistible impulse test. It is followed ONLY in New Hampshire.
4. MPC Test: Under the MPC test (which represents the "modern trend"), a defendant is entitled to acquittal if he had a mental disease or defect, and, as a result, he lacked the substantial capacity to either: (1) appreciate the criminality of his conduct; or (2) conform his conduct to the requirements of law.
1) If D has a defense to the underlying felony, then she has a defense to felony murder.
2) The felony D is committing must be a felony separate and apart from the actual killing (e.g., burglary, arson, rape, sodomy, etc.).
3) The deaths must be foreseeable.
4) Deaths caused while fleeing from a felony are felony murder; HOWEVER, once D has reached a point of temporary safety, deaths caused thereafter are NOT felony murders.
5) At common law, D is NOT liable for the death of a co-felon as a result of resistance by the victim or the police.
6) Under the "proximate cause" theory, felons are liable for the deaths of innocent victims caused by someone other than a co-felon. Under the alternative "agency" theory of felony murder, the killing must be committed by a felon or his "agent" (i.e., an accomplice) with limited exceptions in cases
in which the victim was used as a shield or otherwise forced by the felon to occupy a dangerous place.