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Texas Penal Code 8.01 Insanity Defense

Texas Penal Code Section 8.01: Insanity - Houston Criminal Defense Attorneys


Texas Penal Code Section 8.01 addresses the concept of insanity as an affirmative defense to criminal prosecution. This section specifies that a person accused of a crime may assert the defense of insanity if, at the time of the alleged unlawful conduct, they were unable to comprehend that their actions were wrong due to a severe mental disease or defect.

Key Points

Affirmative Defense: This section establishes insanity as an affirmative defense, meaning that the burden of proof falls on the defendant to demonstrate their mental state at the time of the alleged crime.

Severe Mental Disease or Defect: To qualify for the insanity defense, the defendant must have been suffering from a severe mental disease or defect. This mental condition must have impaired their ability to understand that their actions were morally or legally wrong.

Lack of Knowledge of Wrongdoing: The crux of this defense is that the defendant, due to their mental condition, did not have the knowledge or capacity to recognize that their actions were in violation of the law or societal norms.

Exclusion of Certain Abnormalities: The definition of "mental disease or defect" under this section specifically excludes abnormalities that are solely demonstrated through repeated criminal or antisocial behavior. In other words, a history of criminal conduct on its own cannot be used to establish insanity.

Case Law:

“An affirmative defense to prosecution is available to a person who commits a criminal offense without knowing that the conduct is wrong because of a severe mental disease or defect. See TEX.PENAL CODE ANN. § 8.01 (Vernon 1994).”

Miller v. State, 940 S.W.2d 810, 812 (Tex. App. 1997).

"The law presumes that the accused is sane, and the accused bears the burden of proving by a preponderance of the evidence that he is insane. Martinez v. State, 867 S.W.2d 30, 33 (Tex. Crim. App. 1993); see Ruffin v. State, 270 S.W.3d 586, 591-92 (Tex. Crim. App. 2008) ("Texas law . . . presumes that a criminal defendant is sane and that he intends the natural consequences of his acts.")."

Dung Ngoc Thi-Zeluff v. State, No. 10-18-00171-CR, 3 (Tex. App. Jul. 3, 2019).

"The insanity defense focuses on whether the accused understood the nature of his action and whether he knew he should not do it. Ruffin, 270 S.W.3d at 592; Bigby v. State, 892 S.W.2d 864, 877-78 (Tex. Crim. App. 1994). In the context of the insanity defense, the word "wrong" means illegal. Ruffin, 270 S.W.3d at 592. If the accused knows that his conduct is "illegal" by societal standards, then he understands that his conduct is wrong, even if, due to a mental disease or defect, he thinks his conduct is morally justified. See id. Thus, proof of a mental disease or defect alone is not sufficient to establish an affirmative defense of insanity. Nutter v. State, 93 S.W.3d 130, 132 (Tex. App.—Houston [14th Dist.] 2001, no pet.); see Bigby, 892 S.W.2d at 877-78 ("The issue of insanity is not strictly medical. It also involves both legal and ethical considerations.")."

Dung Ngoc Thi-Zeluff v. State, No. 10-18-00171-CR, 3 (Tex. App. Jul. 3, 2019).


Sec. 8.01. INSANITY.

(a) It is an affirmative defense to prosecution that, at the time of the conduct charged, the actor, as a

result of severe mental disease or defect, did not know that his conduct was wrong.

(b) The term "mental disease or defect" does not include an abnormality manifested only by repeated criminal or otherwise antisocial conduct.

Acts 1973, 63rd Leg., p. 883, ch. 399, Sec. 1, eff. Jan. 1, 1974. Amended by Acts 1983, 68th Leg., p. 2640, ch. 454, Sec. 1, eff. Aug. 29, 1983; Acts 1993, 73rd Leg., ch. 900, Sec. 1.01, eff. Sept. 1, 1994.

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