A defendant cannot be convicted of a crime if they are not mentally competent to stand trial. This would violate constitutional protections for defendants by denying them the right to a fair trial. Competency involves being able to understand the proceedings and play a role in their defense. A lack of competency forms a roadblock to a trial and conviction regardless of how strong the prosecution’s evidence may be. It does not prevent the police from making an arrest or the prosecution from filing charges, but the proceedings cannot go further until and unless the defendant is found to be competent. Moreover, a defendant or their attorney cannot waive the issue of competency. Some states require a defense attorney to ask for a competency evaluation if they believe that there is any possibility that their client may not be competent to stand trial.
An important distinction to understand is that a competency determination applies to the defendant’s current mental state rather than their mental state at the time of committing the alleged crime. Thus, it is different from a defense such as insanity. Incompetency to stand trial is not a defense to the underlying crime. The proceedings can continue normally once the defendant becomes competent again.
Not every mental health condition automatically means that the defendant is incompetent to stand trial. A judge will evaluate competency on a case-by-case basis, usually with the assistance of psychologists. They have the authority to order that a defendant take medication to address a condition if this would make them competent. A judge will need to determine competency early in the process, as soon as it is raised. Either the prosecution or the defense may raise the issue, and the judge also can raise it on their own if neither side does. They may observe signs of incompetency from the defendant’s behavior if they do not appear to understand basic elements of the proceedings.
Competency will be decided at a hearing on the defendant’s fitness to stand trial. Many states provide that a psychological evaluation will be an automatic part of this process, and judges in any state can order this evaluation. A judge likely will rely heavily on the opinion of the psychologist, but they can take their own observations into account as well. They can consider the defendant’s ability to understand the charges, understand the penalties that they may be facing, make decisions, and communicate with their attorney, among other indicators.
Some situations in which a defendant is not likely to be found incompetent are when they lack a certain level of education or are simply not smart. They need to be able to make decisions, but they do not need to make smart decisions. Similarly, they do not need to understand all of the legal nuances of the case to the extent that an attorney would. Defendants who are foreign nationals and who do not speak English fluently will not be found incompetent on that basis. A competency evaluation uses a very lenient standard, and it generally will be met unless a defendant is struggling with a serious mental illness.