A Summary of the Impact of Genetic Research into Behavioral Characteristics for the Criminal Justice System


By Lauren Marshall, 3L – Sandra Day O’Connor College of Law

Over the past several decades, advancements in genetic research have had far-reaching implications in many fields, such as healthcare, insurance, and the law.  While there is still much to be discovered, the knowledge of the scientific community has grown exponentially in many areas of genetic research.  One of the greatest achievements in recent decades has been the Human Genome Project.  The Human Genome Project began in 1990 and was completed in 2003.[1]  During this time frame, scientists mapped and sequenced roughly 20,000 human genes.[2]  Not only did The Human Genome Project make impressive discoveries during its operative period, but it also continues to fuel new and innovative genetic research and biotechnology.[3]   For instance, in the years since The Human Genome Project, 1,800 disease genes have been discovered, 2000 genetics tests are available to consumers and physicians to learn more about genetic risks, and nearly 350 biotechnology products are presently being tested in clinical trials. [4]  The data from this project has the potential to diagnose and fight disease, change human psychology and physiology, and ultimately allow each person to better understand his or her genetic makeup and its potential hazards.[5]

The results of the Human Genome Project have already caused a ripple effect into the current criminal justice system.  For instance, it is common to allow the utilization of Deoxyribonucleic acid (“DNA”) fingerprinting as evidence at the trial level, because DNA fingerprinting is a valuable tool used by law enforcement and prosecutors, allowing them to connect defendants to the scene of the crime with reasonable certainty.[6]  Furthermore, genetic research has led many to believe that individuals have criminal tendencies and are unable to be rehabilitated.[7]  As a result, many jurisdictions created a “three strikes, you’re out” system for sentencing and enhanced detention for known sexual predators.[8]  In addition, research has shown strong genetic correlations between conditions like anti-social behaviors, alcoholism and the propensity to conduct criminal activities, which in turn have been offered by defendants to attempt to exonerate their behavior in whole or in part.[9]

As the criminal justice system seemingly moves forward into a more “geneticized legal system,” the value of genetic evidence has the potential to allow for a better understanding of the facts of the crime and the criminal behavior of the defendant.[10]  Additionally, it is possible that genetics will be a large factor in determining the culpability of a defendant; the individual’s genes could be used to understand behavioral propensities and the appropriate scope of legal responsibility.[11]

Many studies have shown a strong correlation between the genetic makeup of an individual and his or her criminal predisposition.  Specifically, research on twins and adoptees has revealed that one’s genes play a major role in determining whether an individual will engage in criminal activity.  In addition, genetic disorders such as MAOA deficiencies have been shown to increase the likelihood of aggression and criminal conduct.  However, all of these studies have demonstrated that environmental factors also substantially influence an individual’s susceptibility to partake in crime.  Since current research emphasizes the importance of the environment, I do not believe a complete link will be found between genes and criminal predisposition.

Nevertheless, as research continues to advance the understanding of the role between genes and behavior, the criminal justice system will be faced with examining the implications this information will have in the courtroom, both procedurally and legally.  In light of the character evidence restriction under the Federal Rules of Evidence and right to privacy under the Fourth Amendment, it is unlikely that the prosecution will be able to request or use genetic testing for criminal predisposition during the guilt phase, unless the defense first opens the door to such evidence.  Furthermore, the admissibility of criminal predisposition evidence will be evaluated under the Daubert standard.  Since the current understanding of such evidence is highly debated, it is possible that a court may deny its admission during the guilt phase due to its lack of reliability.

Moreover, advancements in genetic criminal predisposition research could have a profound impact on the foundations of our current criminal justice system.  One major impact will be on the theory of culpability, which states that an individual can be held accountable because he acted under his own free will.  Since genetic predisposition evidence has the capability to partially or completely negate the notion of free will, courts will likely deem it inadmissible in determining guilt until a complete link can be shown between a gene and specific conduct.  On the other hand, such evidence has been allowed as a mitigating factor during the penalty phase of a trial, as it relates to the defendant’s character and ability to control their actions.  Another major impact would be on the current theories of punishment.  It is likely that evidence of genetic criminality would preclude the use of retribution, rehabilitation and deterrence, as these theories rely on culpability and a criminal’s ability to modify their behavior.  Until science advances genetic treatment, incapacitation will be the only available form of punishment to protect society from genetically predisposed criminals.

[1] Mark A. Rothstein, The Impact of Behavioral Genetics and the Law and the Courts, 83 Judicature 116, 117 (1999).

[2] Overview of the Human Genome Project, http://www.genome.gov/12011238

[3] Human Genome Project, Nat’l Inst. of Health, (Mar. 29, 2013), http://report.nih.gov/NIHfactsheets/ViewFactSheet.aspx?csid=45&key=H#H.

[4] Id.

[5] Steven I. Friedland, The Criminal Law Implications of the Human Genome Project: Reimagining A Genetically Oriented Criminal Justice System, 86 Ky. L.J. 303, 306 (1998).

[6] Id.

[7] Id.

[8] Id.

[9] Id.

[10] Id. at 307.

[11] Id.

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