Nevada "Insanity" Laws; other Mental Defenses (NRS 174.035)
Explained by Las Vegas Criminal Defense Attorneys

There are some crimes in Nevada that you are not liable for if you are insane or intoxicated at the time.  However Las Vegas courts have a very narrow standard for determining mental incapacity, so it is important you retain counsel to help craft a workable defense strategy.

Our Las Vegas criminal defense lawyers have fought many criminal charges by claiming insanity or intoxication.  Keep reading to learn the law and how we may be able to persuade the prosecutor to drop or lower your charges or else to win you an acquittal at trial.

Insanity defense in Las Vegas, NV

Legal insanity is a complete defense to a criminal act in Nevada.  This means that if the case goes to trial and the jury finds that the defendant was insane at the time of the alleged crime, the jury will acquit the defendant.


In order to determine whether a person is insane, Las Vegas courts follow the M'Naghten rule:  Insanity under M'Naghten is when the defendant was in a delusional state at the time of the alleged offense due to a disease or defect of the mind that prevented the defendant from either:

  • knowing or understanding the nature and capacity of his/her act; or
  • appreciating that his or her conduct was illegal.

Insanity is a very narrow standard in Las Vegas.  Delusional beliefs may qualify as insanity only if the delusion, if it were true, would justify committing the crime.  Let us illustrate this concept with an example:

Example: John suffers from a delusion that Sam is shooting at him, so John shoots Sam.  If at the murder trial John claims he was insane and the jury believes him, they will acquit him.  This is because if John's delusion was true (that Sam really was shooting at John), then John did nothing wrong by defending himself.

Now let us change the example slightly:

Example: John is paranoid that Sam will kill John the next day, so John tracks down Sam and kills him.  If at the trial John claims he was insane, the jury would probably convict him of murder anyway.  This is because if John's delusion was true (that Sam was going to kill him the next day), then John did not act lawfully by tracking down Sam and shooting him first . . . since he was in no immediate danger, he should have instead informed the authorities.

Note that the definition of insanity in Nevada does not comprise mental defects caused by voluntary intoxication.


In order to raise the insanity defense in Nevada, the defendant may either:

  • plead "not guilty by reason of insanity" no less than 21 days before the trial, or
  • claim he/she is not guilty by reason of insanity during the trial

If the case does go to trial, the judge will allow the jury to consider the insanity defense only if the defendant presented evidence during the trial that his/her delusion, if true, would justify the commission of the criminal act.  The jury may then acquit the defendant if they find that the defendant proved he/she was insane by a "preponderance of the evidence."

Whenever a jury acquits a defendant on insanity grounds, the judge will then order the defendant into protective custody for a mental health evaluation.  If the court then finds that there is no "clear and convincing" evidence that the defendant still has a mental illness, he/she will be released.  Otherwise, the defendant will be committed until further notice.

Pleading "Guilty but Mentally Ill" in Las Vegas, NV

Nevada is one of a few states which allows defendants to plead "guilty but mentally ill."  This is essentially the same as pleading guilty . . . the only difference is that the judge may also order mental health treatment in addition to criminal penalties such as prison.

Defendants who choose to plead "guilty but mentally ill" typically do so when the chances of them being acquitted on insanity grounds are small.  The advantage of being found "guilty but mentally ill" over simply being found guilty is that it may look better on the defendant's criminal record . . . it suggests the defendant did not do the crime on purpose and has since received treatment.

A plea of guilty but mentally ill must be entered no less than 21 days before the trial, if there is one.  And if the case does go to trial, the defendant has the burden to prove that he/she was mentally ill by a preponderance of the evidence.

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Intoxication Defenses in Las Vegas, NV

Depending on the circumstances, being extremely drunk or high during the commission of a crime may relieve you of liability in Nevada.  The extent to which intoxication qualifies as a defense turns on whether the intoxication was involuntary or not:

Involuntary Intoxication in Las Vegas, NV

Involuntary intoxication is when the defendant becomes severely mentally incapacitated by no fault of his/her own.  Two common examples of involuntary intoxication in Nevada include someone secretly spiking your drink or you having an unusually adverse reaction to medicine.

Involuntary intoxication is treated like temporary insanity in Nevada.  Therefore if defendants can show by a preponderance of the evidence that they were involuntarily intoxicated during the commission of the crime, and that the intoxication was so severe that they could not know what they were doing or that their actions were wrong, then the jury should acquit them.

Voluntary Intoxication in Las Vegas, NV

Voluntary intoxication in Nevada is when defendants become drunk or high as the foreseeable result of their own behavior (such as drinking or taking drugs).  Because voluntary intoxication is the defendants' fault, Nevada courts are less forgiving of crimes they commit while intoxicated.  Therefore, voluntary intoxication is a valid defense only in limited circumstances . . . .

There are two types of crimes in Nevada:  "Specific intent crimes" and "general intent crimes."  The differences between the two are too complex and confusing to discuss here.  Suffice it to say that voluntary intoxication may serve as a defense only to specific intent crimes.  Examples of common specific intent crimes (for which voluntary intoxication is a defense) include:

Examples of general intent crimes (for which voluntary intoxication is not a valid defense) include:

Note that intoxication is not a defense in Las Vegas unless it is extreme.  Being only "buzzed" or hungover does not qualify as intoxication.

Arrested?  We can help . . . .

If after reading this you would like to discuss the possibility of our Las Vegas criminal defense lawyers defending you, call us at 702-DEFENSE (702-333-3673).  We may be able to get your charges dropped or lowered to less serious charges.  And if necessary we will take your case all the way to trial.

Also see our article about Assisted Outpatient Treatment in Nevada for mentally ill defendants.

For information about California insanity defense laws, go to our informational articles on California insanity defense laws.






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