美国刑事法中的能力减弱辩护制度是基于被告人患有精神病或存在精神缺陷而否定犯罪成立要件中的犯意要素,从而达到否定指控的罪名或减轻罪责目的的辩护制度。虽然对于该辩护制度的存废无论是理论界还是司法实务界均存在一些争议,但该制度目前仍被美国部分州法院适用。能力减弱辩护一般于开庭审理前由被告方向法院提出,同时需要提交被告人患有精神病或存在精神缺陷的证据。在庭审的过程中一般由被告方对其能力减弱的事实承担证明责任,由事实裁判者裁定被告人患有的精神病或存在的精神缺陷是否影响到其被指控的犯罪所需的特定犯意的形成,并作出其是否构成被指控的犯罪以及应否减轻其刑事责任的判决。美国刑事法中的能力减弱辩护制度具有一定的合理性,对完善我国相关的辩护制度不乏启示意义。 The abridgement of defense system in American criminal law bases on the defendant’s mental illness or existence of mental defects to negate the criminal element of the establishment of elements of crime so as to achieve the accusation of negating the charges or defending the purpose of the defense. Although there is some controversy over whether the defense system should be put aside or not, both in theory and in judicial practice, the system is still applied by some U.S. state courts. Weak capacity defense is generally filed before the court by the defendant to the court, at the same time need to submit evidence of the accused suffering from mental illness or mental retardation. In the course of the trial, the defendant generally bears the burden of proof on the fact that his ability is weakened, and the fact judge determines whether the defendant has the mental illness or existing mental defect that affects the formation of the specific criminal intention required for his alleged crime And make a judgment as to whether it constitutes an alleged crime and whether its criminal liability should be mitigated. The defending system of weakening ability in American criminal law has some rationality, and it is not lack of apocalyptic significance to perfecting the relevant defense system in our country.