Ⅰ. Introduction

While the recent development of modern neuroscience has laid the groundwork for questioning the very basis of legal philosophy and criminal jurisprudence in terms of criminal responsibility and justification of punishment, communication between the two disciplines has been relatively lacking. As various researches in the field of neuroscience revealed brain mechanisms related with human cognition, various brain test data have come to be used in courts as evidences for explaining behaviors and their underlying motivations. And the courts themselves have been tasked with new issues, such as determining how to use findings from neuroscience researches in legal proceedings, deciding their relevance to the facts at hand and establishing the standards for application of neuroscientific knowledges to cases involving criminals with brain disorder.
In other words, we need to prepare ourselves in terms of acknowledging the ever growing influence of neuroscience and understanding and accepting neuroscientific technologies that hold great relevant to basic issues in the field of criminal jurisprudence. On the other hand, we need to establish the basis for properly acknowledging and determining the limits of neuroscientific technologies in the legal field and other comprehensive issues related with interpretation and application of neuroscientific knowledges and technologies. In light of the above, we conducted “a preliminary study on convergence between the neuroscience and the criminal jurisprudence” in the first year of the project period, and the outcome of the first study forms the basis for review of the new issues that the neuroscience suggests for the current criminal justice system in a more specified and practical manner, which constitutes the second-year phase of this project.
The theme of this study is described below in three parts: the substantial approach, the procedural approach and correctional treatment for defendants with brain damage or disorder.

Ⅱ. Mens rea and Responsibility under the Criminal Law and Neuroscience

1. Relevance of Brain Damage or Functional Disorder to Criminal Behavior

The term ‘mental disorder’ under Article 10, Paragraph 1 of the Criminal Code of the Republic of Korea refers to biologically caused mental disorder, and the courts have specified different types of disorder over the years. And brain damage is classified as exogenic mental disease.
Through researches conducted by collecting, testing and analyzing brain damage patients of similar conditions, the relevance of specific brain regions to certain behavioral defects has been established. Brain damage researches, however, differ from other types of researches in that the former have to rely on human subjects with brain damages caused by a variety of unfortunate events. In addition, the wide variety of patients characteristics do not allow for easy inference or generalization of relationship between brain functions and brain damages. Furthermore, the very relationship between mental diseases and crimes has been the subject of fierce debates. A number of recent studies, however, reported correlation of substance abuse with violence or sexual crimes. Similar researches have been conducted in the Republic of Korea, which found correlations of varying degrees between criminals and their mental status.
Some might ask if sociopathic criminals manifest the same type of anomaly in their prefrontal regions as brain damage patients do. A study conducted by Adrian Lane dealt with this very issue, in which the researcher found that difference in volumes of grey matter may result in difference in the subjects’ social behaviors. In addition, it would be reasonable to assume that brain damage or functional disorder is accompanied by certain functional deformation or change of shape, and certain disorder of brain function causes changes in human mind and behavior. A number of neuropsychological studies conducted under this assumption have found that functional disorders in certain brain regions or neuropathological manifestations are correlated with criminal tendencies.
It should be noted, however, that the studies cited above do not demonstrate the possibility of brain damage resulting in alarmingly high increase of crime rates. Only in rare cases were any signigicant correlations observed. Moreover, brain damages may occur in a number of brain regions, and different manifestations may lead to different impacts on behaviors. Also worth mentioning at this point is the immense complexity of neuroscientific data such as fMRI images or brain maps, which makes understanding the relevant findings utmostly difficult.
There have been serious debates on whether brain function disorder holds any relevance to crimes, and whether it may be cited as ground for mitigating or excluding criminal responsibility. There are several reasons, however, to conclude that neuroscientific data such as fMRI images may not be sufficient for substantiating such correlation.
First, brain images show the state of the subject’s brain at the time of the test, rather than at the time of the behavior itself. Second, neuroscientific researches so far have been conducted on only limited number of subjects, which makes it difficult to draw conclusions pertaining to a specific case from such studies. Third, abnormal brain function is not a sufficient or necessary ground for mitigating or excluding criminal responsibility, as abnormal function does not necessarily cause abnormal behaviors. The brain images only demonstrate certain correlations: thus, it has been repeatedly pointed out that proving specific causality requires additional evidences that prove that the defendant was not able to control his/her behavior at the time of the crime.

2. Brain Damage, Functional Disorder and Forming of Mens Rea

An actor maybe held criminally responsible only if and when he/she is conscious of being engaged in the relevant act. An actor usually conceives a certain plan, willingness or determination for his/her act, and balance the risks and benefits pertaining to the act before putting it into practice. Such psychological events constitute what we may call the actor’s ‘intention’. And this ‘intention’ holds great importance in the field of criminal law, as it may lead to complete exclusion of the actor’s responsibility.
Criminal responsibility presupposes wrongdoing that is committed knowingly and intentionally, which is why we cannot hold responsible those who do not have, or have only limited consciousness due to brain damage, diabetic shock, etc. Some behaviors, however, may occur without the actor realizing it.
Nueroscientists have been trying to find out who human brain works, and these efforts have led to development of brain imaging, or neuro imaging, technologies that visualize the functions and structure of human brain. This development has resulted in exponential advancement of researches on human cognition, judgment, memory, social cognition and emotion control, etc. And in growing number of criminal cases, brain image or psychiatrical evidences are submitted for the purpose of negating the mens rea of the defendant. And expert testimonies regarding such evidences also have been recognized as useful and relevant in determining the defendant’s competency to be held responsible.
On the other hand, some scholars argue that criminal responsibility should be based on the act itself, rather than the state of the actor’s brain. They maintain that criminal responsibility presupposes blaming the ‘actor’, not his/her brain, and neuroscientific explanation alone do not constitute sufficient ground for negating the actor’s mens rea.

3. Criminal Responsibility of Different Types of Brain Damage

Addiction used to be viewed as a moral issue, but now it has come to be recognized as a form of brain disease, a change partly brought about by development of neuroscience. In particular, various imaging studies have found underlying disruption in certain brain regions of addicted individuals, and established the relation between neural behavior and human behavior, or between certain mental status and activation of complex neural patterns.
As drug addiction and abuse are closely related with criminal behaviors, criminal responsibility of addicted defendants have become an important, and tricky, legal issue. While drug addiction itself is not accepted as a valid ground for defense, it may play a part in mitigating the sentence after conviction. And we should begin to find an appropriate way to define the limit of individual responsibility of drug addicts with defective brain circuits, while taking care not to create new excuses for people with addiction problems.
In light of the above, drug addiction needs to be treated as a brain disease requiring medical attention, and we need to approach this issue by converting to the ‘de-criminalization’ policy accompanied with active medical intervention, which consists of accurate assessment, individually tailored service and social reintegration. Drug courts and problem-solving courts in the United States represent a good example of such a policy: they combine strong supervision with treatment programs, focusing on enhancing the life quality of the addicts and ensuring appropriate treatment of their mental disease and normal life.

Psychopathy is characterized by inability to empathize, no concern for others and anti-social, abnormal behaviors. Psychometirc tests for psychopathy diagnosis measures brain function disorder, and brain imaging technologies are widely used to directly measure brain activities and thereby specify psychopaths. Such neuroscientific methods have shown that psychopathy may be caused by neural damage or disorder that restrict an individual’s ability to function as a moral subject, linking the disease to abnormal electrical reaction in the brain. It may be too early, however, to conclude that neuroscience is fully capable of specifying and diagnosing psychopaths, as the cause, stability and diagnostic usefulness of neural abnormality have yet to be substantiated.
As for criminal responsibility of psychopaths, there has been much controversy regarding whether psychopathy constitutes a valid ground for insanity defense. Most scholars agree that it is not the case, as psychopaths are fully capable of recognizing the meaning of their behaviors, so much so that they deceive or manipulate others around themselves. Under the same note, most courts do not recognize psychopathy or sociopathy as a ground for insanity defense. One may ask, however, if a person diagnosed with psychopath is fully responsible even when he/she is found to be completely incapable of reasonable judgment and decision. To this question, some scholars argue that a psychopath may be found not guilty if his/her psychopathy is so severe as to constitute a mental disease or disorder. One should note, however, that such scholars do not conclude that such psychopaths should be set free. Such arguments are usually linked with medical treatment of such criminals.

The Criminal Code of the Republic of Korea regards persons under the age of 14 as incapable of being held criminally responsible, while other criminal codes put forward different ages for the same purpose. Determining the appropriate minimum age of criminal responsibility needs to be based on consideration of the youths’ developmental stages as well as social consensus of the relevant nation, with participation of and discussion among experts from various fields, including psychology, sociology and criminal jurisprudence.
In this regard, neuroscience has contributed to identifying the significance of various brain regions for each developmental stage, and demonstrating that development of the cortex regions related with high level functions is deterred until the mid~late puberty. Specifically, a number of researches based on brain MRI have showed that neuropsychological defects during childhood significantly affects children’s level of self-control. That is, children may engage in criminal behaviors without being fully aware of the long-term consequence of such behaviors. Such findings present various implications for the criminal justice system. Some argue, based on evidences showing that a child’s brain is not yet fully developed and does not stop growing until early 20’s, that we need to reconsider our current minimum age of criminal responsibility. Some studies even conclude that the age of 21 or 22 is closer to biologically or scientifically defined maturity.
To cite actual cases, the U.S. Supreme Court refused to execute a youth under the age of 18 in Roper v. Simmons (2005), accepting the scientific argument that children under 18 are cognitively and psychologically under-developed.
The Court again mentioned limited responsibility on the same ground in Graham v. Florida, 2010. Those who agree with the Supreme Court maintain that brain images or expert testimonies showing underdevelopment can be used in court proceedings to assist the jury in deciding whether to hold the young defendant responsible. On the other hand, the opponents argue that using underdevelopment of children’s brain in the legal proceedings constitute biological determinism.
In light of the above development, we need to understand that children’s brains are different from those of adults, which may lead to defects in cognitive and decision-making functions. Therefore, we need to reconsider our criminal justice system for youths, in terms of execution, sentencing, treatment and minimum age, etc.

4. New Theories on Neuroscience and Criminal Responsibility

Development of neuroscience and non-interventionist methods such as fMRI has created a new field of ‘social neuroscience’, and kindled the reductionist expectation that neuroscience will solve all our social problems. This reached into the field of criminal law, where findings of neurobiological researches have been used to prove abnormal brain condition or brain damage.
It still remains uncertain, however, how close brain damage is correlated with criminal behaviors. While neuroscientific researches have shown us the true mental state of defendants with mental diseases and helped us finding the cause and solution for violence, they also caused great concern for the criminal justice system due to their possibly deterministic approach: researches on brain disfunction have led the press to use such term as ‘hate circuit’ or ‘compensation center’, as if such emotional reaction is hard-wired into the human brain.
Persons with frontal lobe brain dysfunction (FLD) usually have normal cognitive abilities, but lack the ability to comprehend and control their behaviors, which is why FLD is only rarely cited as a ground for insanity defense under the current insanity defense regime. Under the Irresistible Impulse Test, however, a defendant is not guilty if he/she has a mental disease that renders the defendant incapable of controlling his/her own behavior. Proponents of this test argue that the test will provide people with FLD an opportunity to prove that they are not responsible for the crimes that they were accused for.
In addition, the Korean Criminal Code defines limited mental capability as a ground for mandatory sentence reduction. However, the United States and the United Kingdom recognize ‘partial responsibility’ as a form of limited responsibility for cases involving defendants with brain damage or functional disorder affecting their cognition and decision. Partial responsibility is very meaningful for defendants with FLD or functional disorder, as it is linked with treatment programs for their conditions.

Ⅲ. Use of Neuroscientific Approaches in Criminal Procedures and their Limits

1. Use of Neuroscientific Tools in Criminal Investigation

Finding out if the suspect is lying holds great importance for criminal investigation. Development of neuroscience has led to invention of a possible candidate for neurologically securing evidences of deception by reveling the correlation between deceptive behaviors and our neural system. However, use of neuroscientific technologies for such purposes create other problems related with enforcement of brain function tests and the possibility of forced testimony. Currently there are two types of such technologies: fMRI-based lie-detector and brain fingerprinting.
The underlying theory of fMRI-based lie-detection is that lying activates certain regions of the brain, and we can identify the variables related with lying by measuring activation levels in different regions. Caution is required regarding this technology, however, since the validity of this method is still under controversy, and the technology itself is still in its development phase.
Brain fingerprinting uses a sort of evoked EEG test: it determines presence of certain information in the subject’s brain by detecting electrical signals from the brain while showing the subject various words, phrases or images. That is, we can verify the existence of such information if the brain responds to it. While the science underlying this technology is relatively sound, it has not been independently tested for its accuracy.
As neuroscientific technologies may provide us with powerful investigative tools in the near future, we need to discuss whether drawing inferences about our minds by brain tests enforced by an investigative agency can be accepted as a legitimate investigative method. Involuntary brain test may be viewed as a form of seizure and search, in which case the investigator must have the relevant warrant issued from the court. It is uncertain in this stage, however, exactly how these technologies will affect constitutional protection and due process. Still, we need to be prepared for such brain technology-based investigative methods. Also, pursuant to the due process provisions under the Constitution, enforcement of such tests should be reviewed for compliance with the appropriate standards, based on such factors as safety, effectiveness, testers and location of execution.
Another procedural issue related with neuroscientific technology is whether the suspect may refuse to go through neuroscientific tests based on their right to refuse statement. The right to refuse statement should apply to neuroscientific tests, as they differ from other physical tests by offering deductive evidences regarding the subject’s mental state. But other factors should also be taken into consideration, including whether the tests are necessarily disadvantageous for the suspects or defendants, and whether the legal interest protected by such right is definitely superior to the benefits of neuroscientific tests.
In addition, neuroscientific tests reach into the deepest, private realm of a person’s mind. We should seriously consider whether balancing of interests based on the principle of proportionality is applicable to such a private realm: that is, the issue should be considered in terms of protecting the basic human values and dignity. In light of the above, neuroscientific tests should be enforceable under most strictly restricted conditions, as they accompany violation of one’s innermost private realm.

2. Use of Neuroscientific Evidences in Court Procedures

Neuroscientific evidences are used as evidences for various issues in criminal proceedings, including exclusion of mens rea, insanity defense, future dangerousness and truthfulness of testimonies, appropriate level of sentence, competency to stand trial and applicability of capital punishment. And these evidences are mainly submitted to demonstrate certain brain structures or functions. And truth-seeking based on such evidences is obviously subject to limitation due to other constitutional rights and considerations.
The neuroscientific tests used as evidences in court proceedings pose several issues regarding the defendant’s constitutional rights. First, we need to discuss whether the right to take neuroscientific tests can be recognized as a part of the right of the defendant to defend him/herself. In this regard, the U.S. Supreme Court has laid out three criteria in determining whether the defendant’s access to psychiatric experts constitute one of the basic means for appropriate defense: 1) the interest of the defendant affected by the government’s action, 2) the interest of the government affected by granting expert witness, 3) the value of adding or replacing such procedural protection and the risk of depriving the defendant’s interests by not allowing such protection. Therefore, the state should grant the opportunity for a psychiatric expert to play an important role during a criminal procedure if the defendant’s mental condition is relevant to his/her criminal responsibility and punishment, and the assistance of an expert is crucial to the defendant’s ability to defend him/herself.
In the context of the United States, excluding neuroscientific evidence provided by the defendant may lead to objection based on the right to fair and just trial under the 6th Amendment. The Supreme Court once held that not allowing the defendant to submit evidence constitutes violation of his/her defense right.
Another constitutional issue regarding neuroscientific evidence is violation of the right to jury trial. That is, some express concern that allowing neuroscientific tests as evidences may put neuroscience experts in the position to determine the credibility of witnesses and criminal responsibility of the defendant, rendering the jury meaningless. Even with the use of highly reliable neuroscientific tests, however, the jury will still be tasked with determining the credibility of the neuroscientific evidences, and the complexity of such evidences do not preclude the jury’s role of determining their probative value.
Due to the fact that many of brain fingerprinting studies have not been verified to be reliable, as well as the concern that reliance on scientific technologies may exclude the role of the jury as the fact-finder, the courts have not formed sufficient level of trust towards brain fingerprinting. On other note, the courts in the United States use determine the acceptability of neuroscientific evidences by applying Daubert standard, Rule 702 and 403 of the Federal Rule of Evidence. And the courts approach the issue of brain image evidences in terms of the defendant’s right to defend him/herself. Judging from the above, and remarkable advancement of the relevant technologies, it does not seem so far-fetched to expect to have reliable neuroscientific technologies that satisfy the court’s standards for scientific evidences.

3. Admissibility Standards for Neuroscientific Evidences

Neuroscience is known to be capable of producing powerful evidences by directly inspecting the suspect’s or the defendant’s brain. It should be noted, however, that neuroscientific evidences do not promise direct access to the subject’s lies or specific knowledges: they only provide deductive proof related with the subject’s behaviors. Also, the final answer to what the neuroscience can and cannot tell us can only be given by the evidence laws, not the technologies themselves. And brain image evidences have only limited significance in legal proceedings for several reasons: they require understanding of the underlying science before they can be submitted to courts; brain images are confined to the context of the tasks that were used to create them; there is no consensus on the best fMRI data analysis method for a specific purpose; and there is no standard software, with different labs using different softwares, resulting in varying outcomes.
And the courts themselves are very careful in allowing the use of brain image evidences, as they have not been fully tested, are too uncertain and create too many problems. Similarly, the opponents to the use of neuroscientific evidences argue that brain images lack sufficient effectiveness and reliability, and drawing out legal conclusions from inferences about brain function is too risky, as finding the source of certain behaviors in a certain brain region requires sufficient understanding and knowledge about interconnectivity between each region and function. On the other hand, proponents of the use of brain image evidences maintain that the current resistance to use of such evidences is based on antipathy to the neuroscience itself, rather than sound legal theories. They argue that fMRI evidences are fully capable of satisfying the Daubert standards if neuroscience experts explain conflicting views on the evidences, provide enough supporting data and explain how the evidences were verified.

Determining the admissibility and probative value of neuroscientific evidences should be preceded by reviewing the scientific issues surrounding the technology, including repeatability, validity of experiment design, number and diversity of subjects, technical precision and stability of imaging results, statistical methods and factors disrupting the test results.
Along with review of scientific validity, also required is determining whether the evidence is substantial or explanatory. as the former is subject to stricter review standards. As brain image evidences are usually submitted as explanatory evidences, its admissibility is determined mainly by the judge. However, judges should be guided by the current evidence rules in determining their admissibility: relevance of the data to a specific criminal intention, originality of the evidence image, possibility of manipulation, error or distortion, and refutability of the science that underly the statistics programs used. In addition, the Daubert standard and Rule 702 should also apply, under which the following factors should be reviewed: possibility of error, testability and refutability, peer review, error rate, operation/control standards, publication, general acceptance in the relevant field. Also applied are the standards under Rule 403: unfair prejudice, confusion of the issues, or misleading the jury, unfair delay, waste of time and needless presentation of accumulative evidence.
As stated above, neuroscientific evidences are subject to the standards for admissibility of scientific evidences, such as the Frye standards, Daubert standards, Rule 702. However, these standards and rules have been criticized for being unsuitable for neuroscience, due to the complexity, insufficient peer review and publication, difficulties in presenting the accurate error rate, and insufficient standardization within the field. Therefore, Rule 403, the general rule applied to all evidences, should apply to neuroscientific evidences in tandem with other standards cited above.
While our justice system has been relying on forensic science to a considerable degree, it has yet to achieve consistent and reliable system for reviewing neuroscientific evidences due to lack of systematization, verification, consistency and standardization. Therefore, the judges need to be provided with guidelines for verifying the probative value and reliability of brain image evidences, so that they are not forced into a situation where they have to determine admissibility without any expertise or conviction.

Ⅳ. New Paradigm for Treatment of Criminals with Brain Disorder or Damage

1. Current Development in Medical Science regarding Diagnosis and Treatment of Brain Disorder and Damage

Brain imaging is used in diagnosis and treatment of various brain disorders and damages, including Alzheimer’s, sociopathy and psychopathy, pedophilia and schizophrenia. Various structure imaging tests and functional imaging tests are being performed to diagnose the disease based on the state of the subject’s brain.
To ensure effective application of clinical and forensic data, we need to find biological markers to be used as objective indexes in the future. However, this task has been delayed due to several reasons: difficulty of accessing brain tissues, lack of pathophysiological knowledge and uncertain relations among measurements, etc. Additional researches are required to provide diagnosis and treatment tailored for each individual.
So far, the effect size of finding objective anomaly related with mental diseases through biological methods is relatively small. Application of biological methods to clinical studies, however, will help achieving objective and accurate diagnosis, as well as predicting development of diseases and expected reaction to medicine. With accumulation of more evidences, brain imaging technologies can be useful in diagnosing brain damages and disorders in courts, as well as determining the type of appropriate measures for the defendant. And providing valid and reliable biological markers for brain damages and disorders may change the common perception about brain damages and disorders, so that people may view them as caused by the brain, rather than mere psychological factors. Also, application of the clinical diagnosis above will be useful in assisting diagnosis of brain damage and disorder in the courts, and significantly transform legal definitions of such diseases.
As for clinical effectiveness of treatments for brain damage or disorder, may studies report that improvement through medicine treatment resulted in reduced impulsiveness and violence, as evidenced by carbamazepine and lithium, stimulants and serotonin reuptake inhibitor. Psychotherapy is also reported to produce positive outcomes, but its effectiveness has yet to be substantiated.
Effective treatment for psychopaths have yet to be achieved, and the ‘treatment community’ approach is being suggested as a new possibility for patients with personality disorders.

2. Development of Neuroscientific Technologies and Changes in Diagnosis and Treatment

Brain imaging technologies for mental diseases have been under constant development, but their actual use in clinical contexts is still limited. Likewise, while development of the imaging technologies have led to discovery of important biological markers, we have yet to wait until they can be directly used as guidelines for treatment. And there is another issue of ascertaining whether a problem observed in a local region represents an important phenomenon for the overall brain. Thus, brain imaging researches do not allow for blind study, and are vulnerable to various prejudices, as different studies employ different factors, which lead to different outcomes. Therefore, the research processes for brain imaging studies need to go through stricter review and fair, objective standardization, and need to be subject to stricter peer reviews.

3. Discussion on Medical Judgments of Dangerousness of Different Types of Brain Disorders and Damages

Unlike common perception, various studies on relationship between crime and mental diseases report that the direct influence of mental diseases is limited. There is no clearly observed causality, and the drug abuse/dependency accompanying the disease was found to be a more important factor. That is, most studies conclude that other incidental factors such as drug addiction, age, gender and socioeconomic status contribute more to criminal risks than mental diseases themselves.
In the field of psychiatry, neuroscience has shown the potential to contribute to developing individually tailored treatment models by discovering treatment response factors through measurement of brain metabolism and brain waves. With advancement of image processing technologies, we may be able to witness a system capable of pathological identification and early diagnosis of mental diseases.
Such neuro network approaches contribute to protection of human rights by guiding people to view mental diseases as ‘diseases of the brain’, and improving clinical conditions and brain functions by increasing accessibility to treatment. In addition, neuro network approaches can supply the framework for scientific uation of criminals with mental disorders, so as to establish a treatment model within the justice system to preemptively prevent mental diseases to result in criminal behaviors.

Diversion from detention to treatment within the justice system requires accurate diagnosis and treatment of mental diseases, as there is always a possibility that a defendant may deceive others regarding his/her mental condition. Therefore, it is imperative to secure accuracy and objectivity of psychiatric uation procedures in determining the existence of mental disorder.