The insanity defense is a defense by which defendants in criminal trials can plead not guilty by reason of insanity. This plea acknowledges that the accused did indeed commit the acts constituting the offense charged, but seeks to avoid liability on the ground that they were unable to appreciate or know right from wrong at the time of committing these acts due to their mental state. Because of this, it is considered to be a subset of the diminished capacity defense. Defense attorneys who represent defendants in criminal cases may use an insanity plea as a way to help their clients receive more lenient sentences or acquittal.
The following are criteria for establishing an insanity defense:
1) The defendant had mental illness at the time of the crime.
2) Because this mental illness, he lacked substantial capacity either to appreciate the criminality (wrongfulness) of his conduct or conform his conduct to the requirements of law.
3) This mental disease/defect was severe enough that either
4) Defendant could not reasonably understand what he was doing or that his actions were legally wrong.
5) When brought into forensic psychiatric hospitals, many people are first tested for legal sanity. This is done by the use of the M’Naghten Rules or other guidelines based on similar criteria. The “insanity defense” is an attempt to substitute a defendant’s mental status for their lack of ability to make rational choices or control themselves.
For example, in some cases pathological gambling has been successfully used as an insanity defense by defendants accused of theft and embezzlement because they were not able to tell right from wrong with regards to personal finances.
The Defense predicts that if he is found guilty but insane, his sentence will be much less than what it would be otherwise (at least in countries where this defense still exists). Depending on laws governing criminal procedure within a given jurisdiction, the Defense may be able to argue that the verdict should not stand. In jurisdictions which allow this Defense it is also possible for a defendant to plead guilty but insane. This means that they maintain their innocence but acknowledge that the evidence is such that a jury could reasonably find them guilty.
The Defense will usually request a psychiatric evaluation before the trial begins in order to determine if they believe this Defense would be admissible or worthwhile. After this, a report will be sent to all parties involved in the case and it will include evaluations by psychiatrists who have examined the defendant and who might testify at trial regarding their findings. Since neither psychiatry nor psychology can pinpoint exact causes of mental illness with 100% accuracy, due process requires judges and attorneys to consider the Defense’s claims with great care before allowing them to present evidence.
The Defense will also suggest that their client be submitted to a psychiatric examination which can last anywhere from several hours to several months, depending on the jurisdiction and the Defense’s strategy (how much time and money they have). The Defense has no control over exactly how long this evaluation takes because it is determined by the court and depends on factors such as whether or not there were any previous evaluations and/or criminal records of the defendant. When psychiatric evaluations are ordered, either party may request an independent examination at state expense if they believe it would further their case.
If none of these checks are undertaken then it could result in disastrous consequences for all parties involved because, for example, the Defense may be wrong about whether or not their client is legally insane. This could result in either an innocent man being sent to prison for many years, or a guilty person going free if they are found not guilty by reason of insanity.
During this period between arrest and trial, most jurisdictions give defendants the option of pleading guilty but insane. Defendants usually prefer this to having the Defense use an insanity Defense because it allows them to receive both psychiatric help through institutionalization and significantly reduced time in prison rather than being found Not Guilty by Reason of Insanity which would keep them in prison indefinitely with no chance for parole. However, if he pleads not guilty then he will have to wait until after his trial before being sent to a psychiatric hospital or institution. He will usually be held in custody in the meantime, though this varies with jurisdictional preference and resources.
The Defense does not always wait for their client to enter a plea (it can take years) before requesting psychiatric evaluation; sometimes they request it even before charges are filed. Defense attorneys may also choose to submit evidence of mental illness without asking for an examination themselves when they believe that the prosecution has already obtained convincing evidence of insanity on its own (e.g., videotapes). Defense attorneys cannot force their clients to undergo examinations but many defendants cooperate because being found insane would provide them with desirable legal outcomes if convicted.
During trials, Defense counsels have two primary goals: establishing whether or not their client is Not Guilty by Reason of Insanity and building an airtight Defense for their client in case the prosecution attempts to pursue a conviction. To establish NGI, Defense attorneys generally try to provide evidence that their client has serious mental illness or defect. Defense counsels must be sure not to mention any previous criminal convictions because previous bad acts are generally inadmissible unless defense lawyers can show that they are so similar to the current charges that they are relevant.
Defense attorneys often call multiple psychiatrists, psychologists, or other medical experts who have studied their client before trial so that jurors can hear from several different professionals with different opinions about their diagnosis(s). Defense witnesses also testify during the Defense’s presentation of evidence while prosecutors cross-examine them, then return for rebuttal after Defense attorneys finish calling witnesses. Defense counsels may also call scientific, medical, and/or other expert witnesses to show that their client’s mental illness or defect caused him to commit the crime, negating the element of “intent” required for a conviction.
Trial Defense strategy often depends on whether or not they believe their client is likely to be found Not Guilty by Reason of Insanity or guilty but insane because there are different legal consequences in each case. If Defense attorneys believe that their client is likely to be acquitted as Not Guilty by Reason of Insanity, then they will present all available evidence about his psychiatric history and current condition but avoid mentioning any previous criminal convictions except those which are so similar to the charges being brought against him that it is relevant.
Defense attorneys also often emphasize the good character of their client in order to provide jurors with an alternative explanation for the crime (e.g., “he killed his father because he was appalled by his incestuous relationship with his sister, not because he’s evil”). Defense counsels call scientific, medical, and/or other expert witnesses who explain to jurors all about mental illness and how it caused their client to commit the crime(s). Defense lawyers then emphasize that insanity is a permanent mental condition that cannot be treated or controlled like other diseases.