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Intellectually Disabled or Mentally Ill: Competency to Stand Trial and the Insanity Defense

This week, the Supreme Court of the United States (SCOTUS) issued its opinion in Moore v. Texas (read it here).  This case is not only a victory for Texas Death Row inmate Bobby Moore; it’s also a major event in Texas criminal law.

Why?  SCOTUS has ruled that the Texas legal procedure for determining if someone has an intellectual disability is unconstitutional.  It’s a big deal.  For more on the impact of this case, read “Opinion analysis: A victory for intellectually disabled inmates in Texas,” by Amy Howe published March 28, 2017, at SCOTUSBlog.Com.


Mentally Ill or Intellectually Disabled

Two Separate Things: Intellectually Disabled and Mentally Ill

All too often, criminal defense lawyers are approached by family members or loved ones who explain that the accused suffers from some kind of issue that compromises his or her ability to live in some way.  This impacts their daily life, and it’s explained that it should be a factor considered by the police and prosecution as well as any judge and jury.

Many people who suffer from these issues cross paths with law enforcement.  All too often, they end up charged with crimes and serious offenses.  This is true regardless of whether or not they are guilty of the crime itself.  It is also true whether or not they have the capacity or capability to understand what was happening at the time or what is happening to them now, in the criminal justice system.

According to the National Alliance on Mental Illness (NAMI), approximately fifteen percent (15%) of men and thirty percent (30%) of women who are arrested by police and jailed suffer from a serious mental illness.

In Texas, the disproportionate amount of people behind bars who are mentally ill is a serious problem.  These people may or may not be able to hire a lawyer or make bail.  They may not be given treatment or counseling while they are kept behind bars, either.   It’s a huge issue.  See, “Overincarceration of People with Mental Illness,” by Kate Murphy and Christi Barr, published June 2015 by the Texas Public Policy Foundation.

However, from a legal standpoint, it’s important to distinguish between “intellectually disabled” and “mentally ill.”  Why?  Those are distinctions that have been made in the criminal law.

1.  Intellectually Disabled

Those who stand accused of a crime who have impaired mental development are considered to be intellectually challenged or “intellectually disabled.”  This is what Bobby Moore is arguing in his appeals to avoid the death penalty here in Texas.

In earlier times and SCOTUS precedent, this was termed “mental retardation.”  See, e.g., Atkins v. Virginia, 536 U.S. 304, 122 S. Ct. 2242, 153 L. Ed. 2d 335 (2002).


At one time, defendants who are intellectually disabled were to have three things, according to the definition of “mental retardation” given by the American Association on Intellectual and Developmental Disabilities:

  • significantly sub-average intellectual functioning;
  • concurrent and related limitations in two or more adaptive skill areas; and
  • manifestation before age eighteen.

That definition was later revised by AAIDD to “… a disability characterized by significant limitations both in intellectual functioning and in adaptive behavior, which covers many everyday social and practical skills.”

IQ 70 or Below

Another test for finding intellectual disability is provided by the American Psychological Association (APA).  Under APA’s DSM standards, an accused is intellectually challenged if his or her IQ score is lower than or equal to 70.

One of the big issues in Moore v. Texas was which definition to apply in order to decide if Bobby Moore was indeed mentally challenged.

2.  Mentally Ill

Mental illness is entirely different from intellectual disability.  Someone who is suffering from mental illness has an emotional and behavioral issue.  This is independent from their ability to think (intellectual ability) which can be very high.

Also, mental illness may be changed and cured with therapy and/or drugs, unlike intellectual disability.  Additionally, mental illness may come and go during someone’s life while intellectual disability is readily apparent during childhood and obvious by the time of legal majority (age 18).

Diagnostic and Statistical Manual of Mental Disorders (DSM)

Mental illnesses may or may not be recognized in a court of law.  Expert opinion must be provided with a diagnosis of the accused’s condition.  Common mental illnesses suffered by the criminally accused are bipolar disorder and schizophrenia.

Can the Accused Be Tried?  Mental Competency to Stand Trial

Sometimes, the prosecutor does not get the choice of whether or not to proceed to trial because the accused cannot be tried under the law.   Convicting someone who is mentally incompetent violates their constitutionally protected due process.  Pate v. Robinson, 383 U.S. 375 (1966).

Accused Is Not Able to Help In His Defense or To Understand the Proceedings

Federal law (18 U.S.C. §§ 4241 et seq.,) provides that either the defense attorney or the federal prosecutor may file a motion with the court to determine the competency of the accused to stand trial.

From the statute, he cannot be tried for any crime if:  “… there is reasonable cause to believe that the defendant may presently be suffering from a mental disease or defect rendering him mentally incompetent to the extent that he is unable to understand the nature and consequences of the proceedings against him or to assist properly in his defense.”

Here, someone who is mentally ill or intellectually challenged may be found incapable of being tried for any criminal charges.  However, proving this will depend upon the accused’s situation.

If it is due to mental illness, for instance, then the expert opinion of a psychiatrist or psychologist of his mental illness and its prognosis must be provided to the court.

Insanity Defense at Trial

It is an entirely different legal argument for the accused to assert mental illness or intellectual capacity as a defense to the charges brought against him or her.  The insanity defense is recognized both in Texas and in federal law.

Accused was Insane at the Time of the Crime

Here, the issue is the mental state or condition of the defendant at the time the crime happened.  When the offense occurred, what was the mental state of the accused?

If the defendant is found to be insane at the time that the crime was committed, then he has successfully defended against a finding of guilt.

In federal law, the Insanity Defense Reform Act of 1984 controls the insanity defense in federal prosecutions.  Here, the defense must prove at the highest possible evidentiary standard (clear and convincing) the insanity or mental defect of the defendant at the time.   If successful, the defense may proceed to a federal commitment proceeding as provided under the Act.

Constitutional Protections and Intellectually Challenged or Mentally Ill

From a defense perspective, it is of paramount importance to begin the task of defending the intellectually challenged or mentally ill accused as soon as possible after law enforcement begins its suspicions, much less its arrest and incarceration of the defendant.

This is because someone who is suffering from mental illness or who is intellectually disabled is extremely vulnerable to having his or her constitutional rights violated.

Consider the following rights guaranteed to all accused and how easily they can be thwarted when the accused is mentally ill or intellectually challenged:

  • Fourth Amendment Protection against Unreasonable Search and Seizure;
  • Fifth Amendment Protection against Self-Incrimination;
  • Sixth Amendment Protection against Being Tried More Than Once for a Crime (Double Jeopardy); and
  • Sixth Amendment Right to a Speedy Trial.

People from all socioeconomic backgrounds may be intellectually challenged or mentally ill.  Collectively, they are the most vulnerable defendants in any criminal proceeding and all too often, the most victimized.


For more information, check out our web resources, read Michael Lowe’s Case Results, and read his in-depth article,” Pre-Arrest Criminal Investigations.”



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