형법은 일반적으로 대부분의 사람들이 그들이 범한 범죄에 대한 책임을 지기 위해 충분한 일반적 지능과 정신능력을 갖고 있다고 가정한다. 그러나 형법은 범행 당시에 하나 이상의 행위자의 중요한 정신능력이 현저히 결함되었음을 증명하는 때에는 피고인의 형사책임을 면하거나 감해주는 기회를 제공한다. 이처럼 행위자에게 범죄 이외의 다른 행위능력이 존재할 때에만 범죄충동을 억제하지 않고 위법한 행위로 나온 데에 대한 책임을 물을 수 있으므로 책임비난의 전제조건으로서 자유의사의 존재증명과 관련된 책임능력이 문제된다. 따라서 본 논문에서는 미국의 M`Naghten Rules, The Durham product test, Model Penal Code, 1984년 정신항변개혁법(The Insanity Defense Reform Act of 1984) 등을 고찰하고, 우리 형법상 심신장애자(심신상실자 및 심신미약자)에 대한 입법의 태도를 비교·검토한 후, 미국법에 기초한 비교법적 관점에서 형사정책적 시사점은 무엇인지 여부를 살펴보고자 한다.

The criminal law generally assumes that most people have mental and psychological capabilities sufficient to hold them responsible for the crimes they commit. Accordingly, the criminal law assumes people know the law and have free will. Their abilities to know and to choose(or, put in psychological terms, their cognitive and volitional capacities) are bedrock premises of criminal responsibility and underlie all philosophical theories of punishment. Meanwhile, the criminal law does provide limited opportunities for a defendant to avoid or less his responsibility by demonstrating that one or more of his important human capacities was significantly impaired when he committed the criminal act. Defenses such as insanity, infancy, intoxication, and diminished capacity are among the more important of these opportunities. The defense of insanity is litigated at the criminal trial. But the insanity defense has been under heavy attack recently. The public becomes upset when individuals who intentionally engaged in harmful conduct are acquitted by reason of insanity. There are also common misconceptions about the use and consequences of this defense. So, I will study on the M`Naghten Rules, The Irresistible Impulse Test, The Model Penal Code Test, The Federal Insanity Test, The Guilty but Mentally Ill Defense, The Insanity Defense Reform Act of 1984 in relation to the defense of insanity in this treatise.