Guide to the Insanity Defense in Louisiana



The Louisiana law states if the circumstances indicate that because of a mental disease or mental defect the offender was incapable of distinguishing between right and wrong with reference to the conduct in question, the offender shall be exempt from criminal responsibility.  This old law is known as the M'Naughten Rule.  Louisiana is among a minority of states still holding to this rule and the courts rigorously enforce it, along with its limitations. 


The insanity defense is often referred to as “temporary insanity.” Temporary insanity is commonly thought of as a mentally well person losing their mind for a short time while committing a crime, then regaining sanity afterwards. Therefore, they were only insane at the time of the offense, because they aren’t really an insane person. This is not how Louisiana law views the insanity criminal defense.


Don’t confuse this with “blacking-out” or getting so mad that you “see red” and just lose all control. The insanity defense in Louisiana is specifically for not understanding right from wrong because of a mental disease or mental defect. Diminished capacity does not constitute legal insanity nor does the concept of irresistible impulse. Therefore, losing control due to anger, intoxication, compulsion, amnesia, or other emotions won’t satisfy the insanity defense in Louisiana. 


Procedure for the Insanity Defense


Insanity Plea

The defendant must first enter a plea of not guilty and not guilty by reason of insanity at the Arraignment. It is a dual plea. If the defendant only enters a not guilty plea at the Arraignment, he can change it later, upon a showing of good cause. 


Proof of Insanity - Preponderance of Evidence

The defendant then must prove by a preponderance of the evidence that he was so insane at the time of the offense that he did not understand right from wrong.  The defendant must show the court that it is more probable than not that due to a mental defect, he didn’t understand right from wrong at the time of the offense. This burden of proof is less burdensome than beyond a reasonable doubt. The defendant proves this by calling mental health physicians who have examined the defendant to testify. The prosecutor can cross-examine these doctors to try to prove the defendant is malingering, aka making it up.


In determining the question of the sanity or insanity of the defendant at the time of the commission of an offense, the jury must consider all of the evidence bearing on the defendant's mental condition, including the testimony of experts and of other witnesses, and the conduct and actions of the defendant.  The jury gets to decide whether or not the defendant carried his burden of proof and established that he did not understand right from wrong.


To be victorious on the criminal defense of insanity and get a not guilty verdict, the jury must find the following:

(1) that the state proved beyond a reasonable doubt that the defendant did commit the offense charged, or a responsive offense; and

(2) that the defendant established by a preponderance of evidence that he was unable to distinguish right from wrong with respect to the conduct in question at the time of the offense;


insanity defense in louisiana


After the Defendant is Found Not Guilty


If the insanity defense is successful and the defendant is found not guilty by reason of insanity, he is not free to leave. In fact, the judge must remand the defendant to jail or a mental institution until he is found to be nondangerous to himself or others.  The jury should be told this information prior to deliberating because it will protect the defendant because the jury will know that he won’t just go free. The defense attorney can ask the judge to instruct the jury on this.


Technically, the defendant could be stuck in a mental institution for the rest of his life after a not guilty by reason of insanity verdict. Even though he won the criminal case, he’s still locked up. On the other hand, he could soon be found to understand right from wrong and all the sudden become tip-top mentally. If the psychiatrist believes he is mentally healthy, he must be released. 


The criminal defense of insanity or temporary insanity is a very difficult defense to prove and is only effective in limited circumstances. However, since it is a defense that results in an acquittal, our criminal defense attorneys always consider its use.

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