Jun 25, 2020 in Society

Behavior Science and the Criminal Justice System


In respect to behavioral science and the criminal justice system, a defendant has the right of undergoing the various tests that provides information regarding legal insanity before he/she can stand for trial. In addition, a defendant can either be deemed legally insane or termed to have diminished capacity in order for him/her to competent to stand trial. The performance of the criminal justice system in the prosecution of individuals is heavily dependent on human behavior aspects such as their competency to stand trial and their mental capacities.

Competency to Stand Trial

The criminal justice system provides that defendants who are accused of offences and ought to appear in court should be in a position of comprehending and participating in the legal proceedings. This requirement exists with a view of promoting dignity, accuracy in addition to autonomy. In respect to the criminal justice system, dignity and fairness demands that the individuals who are subjected to the state resources in the course of a criminal proceeding should be aware of the proceedings. Moreover, the impaired cannot be placed on trial as this is considered a challenge to legal processes dignity and fundamental fairness conceptions. To add on, a criminal defendant should have the ability to provide information that is helpful to the defense at hand. He/she should be able to challenge the allegations that are made against him/her. Hence, he/she should not have a mental disorder as this might lead to the provision of information that is less accurate thus leading to unjust verdict and outcome. Therefore, the criminal justice system invests in decision making that is accurate hence requiring the accused to have the basic capacities for involvement in the criminal proceedings. Hence the law provides that the accused should have the capacity of making decisions in regard to crucial legal strategies and the decisions regarding his/her involvement in the legal procedures.

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Legal Insanity (McNaughten rules) and Medications

Basically, criminal defendants found to be legally insane are not convicted of their offences because of mental defect or disability. Therefore, the criminal justice system employs various legal tests in determining if the defendant is legally insane or not. One of these legal tests used is the McNaughten rule. The McNaughten rule is also referred to as the right or wrong test. The McNaughten rule emphasizes on whether the criminal defendant was aware of the nature of the crime he/she was being involved with or comprehended the right from the wrong at the moment the crime was committed.

Therefore, the McNaughten rules provide that an individual is deemed legally insane is he /she was not capable of knowing the actions he /she was engaging in during the time a criminal offence is committed. This rule goes hand in hand with the culpability conception regarding criminal law. That is, a defendant is deemed not culpable of actions committed because of psychological infirmity. The second rule provides for the ability of a defendant of determining whether his/her actions were not right. In this case, despite the fact that the defendant was aware of what he/she was engaging in, the defendant is considered insane if he/she is not able recognize wrongfulness as far as the act that is carried out is concerned.

Diminished Capacity

Diminished capacity is a doctrine that provides an opportunity to a defendant of avoiding liability to a crime by showing that his /her mental capacity was much diminished to a point that he/she was not in a position to have the intent of committing the crime he/she is being charged with. Therefore, the defendant should prove that he/she lacked the intent that is required for a crime to be committed because of mental impairment. In this case, the lack of sanity is not invoked with a view of disapproving intent. Rather, it is employed to prove that the defendant did not have the basic capacity that could have enabled him/her to shun away from engaging in a behavior that can be termed as morally comprehensive simply because he/she did not understand the wrongfulness of the act he was doing or he/she was not able to control his/her actions. Thus, if the evidence that is provided fails to prove that the defendant was legally insane, evidence can be provided for proving that a defendant had diminished capacity.

Role of Behavioral Scientists (Psychiatrist) in Testifying in Court and their Duties and Responsibilities

Behavioral scientists or rather psychiatrists have various roles and responsibilities while testifying in courts. Firstly, they have a role and responsibility of evaluating competency to stand trial. Psychiatrist conducts competency evaluation with a view of determining that a defendant has the required mental capacity to comprehend the charges levied against him/her and therefore assist his/her attorney. The psychiatrist thus has a right to a right to be present during an individual’s trial and face the accusers of the defendant as provided by the constitution of the United States.

Secondly, the role and responsibility of a psychiatrist in a court is to act as an expert witness. In this case, forensic psychiatrists are given the responsibility of acting as an expert witness. Thus, the psychiatrist prepares a report that is detailed before testifying in the court. Hence, as an expert witness, the forensic psychiatrist has the roles and responsibilities of providing opinion that is independent to the court. He/she is therefore given permission to testify in court in regard to opinion matters under the circumstances whereby the matters in question cannot be ordinarily understood by the fact finders such as the judge or the jury. Hence, the psychiatrist provides explanations regarding his/her opinion on the matter in question by giving the crucial concepts and approaches as well as the psychiatry methods used.

Furthermore, a psychiatrist provides information to the court regarding the mental state of a defendant. This helps the court in determining whether a defendant was in a position of comprehending what he /she was engaging in at the time the crime was committed. The psychiatrist used various tools in determining the nature of the crime. These tools are the McNaughten rules, the Durham rule and the ALI test. Additionally, psychiatrists have a role and responsibility of caring for the prisoners that is, those in jails and prisons and the mentally ill who have engaged in criminal acts such as the ones who have been identified as guilty by the insanity reason.


In conclusion, before an individual is declared competent to stand for a trial, he/she should be able to understand the charges that are being made against him and thus communicate effectively. Therefore, he/she undergoes various tests that provide a measure of sanity such as the Mcnaughten rule which determines if the defendant knew that whatever he/she was engaging in was wrong or right. However, if an individual is not proven to be legally insane, he/can be proven to have diminished capacity therefore enabling him/her not to stand for a trial. Apart from this, psychiatrists have various roles and responsibilities in court such as acting as an expert witness, determining a defendant’s competency to trial and providing opinion on the mental state for the defense and the prosecution.

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