Perspective Chapter: Criminal Responsibility

Abstract

Contemporary criminal law aims to balance the public’s need to punish harmful behavior with the moral choice of the individual agent who causes harm. The principle of individual criminal responsibility in criminal law focuses on human actions and omissions as the foundations of guilt. Although the debate on free will and agency continues to play a role in contemporary criminal law, criminal responsibility is based on a normative understanding of these notions. This understanding presupposes human agency and the capacity to appreciate the wrongfulness of one’s actions and the ability to conduct one’s behavior accordingly. However, when this capacity is affected by internal or external circumstances, criminal responsibility can be excluded or diminished. This chapter focuses on the different ways of understanding criminal responsibility among various legal systems by comparing the definition and scope of individual criminal responsibility, culpability, and the place of strict responsibility within criminal law and later compares some of the more common defenses affecting the criminal capacity of the defendant: insanity, diminished responsibility, intoxication, and infancy. These defenses shall be compared according to various common law and civil law systems according to their definitions, fields of application, and legal consequences.

1. Introduction

Contemporary legal systems try to strike a balance between the public’s need to punish harmful behavior and the moral choice of the individual agent who causes harm. This approach creates a twofold reason and source for a punishment corresponding to the crime: harm and responsibility.

The law defines actions and omissions that constitute harm or, in some cases, clear and imminent danger to a public good. This harmful act must be prescribed by a previously published law that clearly and foreseeably defines it under the principle of nullum crimen sine lege (no punishment without law). It is generally understood that punishment must correspond to the degree of public harm; thus, more harmful behavior is subject to greater punishment. This proportionality of punishment is necessary for both deterrence (in the form of general and special prevention) and retribution, or the restoration of public order, which are the established purposes of criminal punishment [1].

A basic tenet of criminal law is that the basis of criminal liability is the voluntary action of the individual [2]. This presupposes a human agency and choice based on the assumption of free will. This presupposition brings us to the principles of individual responsibility and guilt in criminal law, which will be analyzed further below.

2. Individual criminal responsibility, human agency, and normativity

2.1 The principle of individual criminal responsibility in criminal law

Criminal law differs from other areas of law in that it focuses on human actions and omissions as the foundations of guilt. This does not rule out the criminal liability of corporations and legal entities, as most legal systems accept this responsibility as part of their criminal law [3]. However, in countries such as Germany and Turkey, the principle is understood to exclude the criminal liability of legal entities and only punish natural persons [4, 5, 6].

The actual meaning of individual responsibility is apparent in the fact that people cannot be punished for others’ actions or omissions. This principle effectively prohibits vicarious liability (liability for the actions or omissions of another person) under criminal law. Thus, moral responsibility can be considered a necessary condition for criminal liability. However, criminal liability may arise from a failure to exercise a duty to effectively supervise the actions or omissions of other people, typically, employees. This kind of liability can still be generally associated with the personal guilt of the supervisor [7]. Additionally, special modes of liability, such as indirect perpetration, command responsibility, and complicity in crime, are accepted as concordant with the principle of individual responsibility. Particularly in international criminal law, command responsibility is understood to encompass the liability of military and non-military commanders for crimes committed by people under their effective command and control (or, when applicable, effective authority and control), as provided by the Rome Statute of the International Criminal Court, Article 28 [8, 9].

However, as stated above, the reasoning behind the acceptance of human behavior as the source of criminal responsibility lies in the presupposition of human agency. Agency defines humans as both the subject and the object of criminal law. Only a person who had some degree of control over their actions and omission can—or, at least, should—be considered an individual deserving punishment

2.2 The role of personal guilt in criminal responsibility

The premise of individual criminal responsibility is further developed by the principle of guilt, according to which criminal responsibility can only be based on a guilty action or omission (nulla poena sine culpa, no punishment without guilt) and must have been able to make a free choice between what is legally right and legally wrong and must have chosen the wrong alternative over the right alternative. In other words, people cannot be blamed for their actions or omissions if they “could not help doing it” [10].

In his famous dissenting opinion, Judge Rubin postulated this principle: “An adjudication of guilt is more than a factual determination that the defendant pulled a trigger, took a bicycle, or sold heroin. It is a moral judgment that the individual is blameworthy. Our collective conscience does not allow punishment where it cannot impose blame. Our concept of blameworthiness rests on assumptions that are older than the Republic: man is naturally endowed with these two great faculties, understanding and liberty of will. Historically, our substantive criminal law is based on a theory of punishing the vicious will. It postulates a free agent confronted with a choice between doing right and wrong, and choosing freely to do wrong” [11].

The normative nature of this choice makes a distinction between ethical and legal reasoning and focuses on what is legally right or wrong based on common values rather than personal ones [12]. Thus, a person deciding to break the law based on his or her ethical convictions can still be regarded as a criminal, while a person committing ethically dubious deeds cannot be punished if his or her behavior conforms to the law in force or even if that behavior, while illegal, has not been defined as a criminal offense.

The definition and scope of the principle of guilt are not uniform across criminal legal systems. In most civil-law countries like Germany, it is understood that strict liability offenses violate this principle, no person can be punished without personal guilt and blameworthiness, and the burden of proof cannot be reversed and laid on the defendant [6]. In contrast, common-law systems such as England and Wales, Canada, and the USA accept strict liability offenses or strict responsibility in criminal law, particularly in cases of minor infractions [7]. In these cases, the culpability of the offender does not need to be present or bound to a presumption that needs to be proven wrong to exculpate the defendant [13].

In civil-law systems, such presumptions would most likely be seen as violating the principle of guilt. However, in common-law systems, strict liability offenses can be punished with imprisonment. In these cases, the lack of culpability in a concrete case may result in a mitigated sentence but does not necessarily change the nature of the penalty, as criticized in [14].

There is one aspect of the principle of guilt where it is possible to observe a wide consensus among legal systems: that criminal punishment must be proportional to guilt. Even if the same amount of damage has been caused by two different actions, punishment must be separated for negligent and intentional behavior, and further distinctions should be made for different degrees of mens rea, such as premeditation, direct intent, recklessness, and negligence.

The Turkish Constitutional Court enforces the principle of guilt in its judgments as part of the constitutional principles of the rule of law and individual criminal responsibility (Articles 10 and 38 of the Turkish Constitution). According to the Turkish Constitutional Court, a leading feature of contemporary criminal law is the adoption of responsibility based on personal guilt. (…) Thus, modern criminal law has left absolute liability and accepted the principle of ‘no punishment without guilt’ as a basic principle” [15]. The Turkish Supreme Court (Yargıtay) goes further by interpreting the law as not allowing aggravated assault and battery to be punished at the same level if the act is committed through dolus eventualis (indirect intent) when compared to direct intent. According to Yargıtay, “(t)he fact that in both cases [direct vs. indirect intent] the punishment should be the same would not conform to the notion of criminal justice or to the purpose of the legislator to provide a lesser degree of punishment for crimes committed with dolus eventualis” [16].

2.3 The illusion of free will and normativity of criminal responsibility

Of course, the legal paradigm based on free choice was, and still is, not without strong criticism. The first wave of criticism against the premise of moral agency was the rise of positivism in the first half of the 20th century. Ferri famously argued that the moral agency of humans was an illusion; all human behavior was based on the laws of causality, and a scientifically accurate criminal law ought to reject the notion of free will and instead base its legitimacy on the notion of necessity [17]. Criminal behavior is not the result of a moral choice by the perpetrator; rather, it is understood as a symptom. According to him, the purpose of punishment should not be to deal with the symptoms but to cure the underlying illness. This meant that criminal law should not focus on the crime, but on the criminal. It should try to understand why the criminal had committed the crime and try to eliminate the underlying reasons. Thus, the real purpose of punishment should be the rehabilitation of the criminal and the protection of the public from the danger posed by the criminal. To its full extent, this positivist system required the elimination of the principles of legality and individual responsibility, as well as punishment in the classical sense. Punishment should not be prescribed by law and applied by lawyers; rather, scientists should decide what measures to apply to criminals to eliminate their dangerousness to society [17, 18].

Positivism, as Ferri proposed, was never applied to this extent, although it had a significant impact on criminal legal systems [19]. Although legality and individual criminal responsibility remain the basic principles of criminal law, the classification and treatment of criminals for purposes of resocialization has entered the penitentiary system. In addition, positivism affected special measures applicable to recidivists and other especially dangerous criminals. Other effects of positivism include probation and the early release of criminals who do not pose a threat to society. Finally and, for the purposes of this chapter, most importantly, positivism caused the introduction of a new system of measures applicable to people who are deemed to lack full moral agency: minors, people with limited capacity, the legally insane, and so on [20].

The debate on free will and agency continues to play a role in contemporary criminal law. A major criticism directed against the premise of agency and choice of the perpetrator arises from recent findings in neuroscience. The famous Libet experiments, where it is shown that decision-making processes mainly take place in the unconscious mind, question the essence of the freedom of will. In these experiments, Libet et al. used electroencephalograms to measure the activity in the supplementary motor area (SMA) of subjects who were asked to note when they were consciously aware of their choice to flex their muscles. The experiment showed that conscious choice followed the brain activity for approximately 350 ms [21]. Although Libet denies that his experiment is incompatible with the idea of free will on the grounds that people can consciously choose to stop the process and not comply with the decision formed in the subconscious mind, the debate on what this means for the purposes of subjective criminal responsibility is ongoing [22].

It should be noted that contemporary legal doctrine considers human agency as a normative notion that is not necessarily affected by any conceived determinism of the decision-making process. Thus, criminal responsibility is understood to be related to the “illusion of free will,” rather than free will itself. Contemporary criminal law, as a social construct, presupposes the normative paradigm that guilt is based on human agency and the free choice of the offender and can work on this presumption unless, or until, it is replaced by a more efficient construct [12, 23].

3. Defenses and criminal responsibility

3.1 The role of defenses in criminal law

In most criminal legal systems, it is generally accepted that actions committed under specific circumstances constitute an exception to liability. However, the nature and effects of these circumstances vary significantly across different jurisdictions.

In civil-law countries, defenses are divided into causes of justification and excuse and are seen exclusively as part of substantive criminal law. Causes of justification, such as legitimate defense, are considered to bring the action in full conformity with the law, resulting in a full exoneration of the defendant. In contrast, causes of excuse do not affect the illegitimacy of the action but provide an exculpation for the defendant; as a result, the defendant cannot be punished with a criminal penalty but may be subject to special preventive measures. Turkish criminal law distinguishes between verdicts of “exoneration” vs. “not to be punished” (Turkish Criminal Procedure Code article 223): whereas the former would result in a complete lack of criminal sanction, the latter allows for measures taken for the confiscation of proceeds from the crime, as well as measures for the rehabilitation of children and mentally challenged criminals.

Jurisdictions under the influence of common law do not distinguish between justification and excuse very strictly; although the distinction is expressed theoretically, in practice, both form part of the broader category of defenses. In addition, in common law, defenses are in close contact with the law of evidence, which is part of the procedural law.

This distinction also affects the burden of proof in many defenses. In civil law countries, criminal procedure does not generally accept presumptions of guilt, and any defense falls under the general presumption of innocence: the court may only reject a defense if it cannot be shown beyond reasonable doubt that the defense did not occur. In contrast, for many common-law jurisdictions, the so-called affirmative defenses, which comprise all forms of excuse, lay the burden of proof partly on the defendant, who must introduce credible evidence for the occurrence of the excuse.

The category of exculpating defenses, or excuses, refers to circumstances that affect the defendant’s ability to understand the legal and social nature of his or her conduct and the capacity to conform his or her behavior to this understanding. Any lack of this understanding or capacity would mean that the defendant cannot act as an agent that can freely choose between right and wrong and thus cannot be considered guilty of his or her conduct.

While some defenses affecting this freedom of choice may have a temporary or permanent effect on the personal decision-making process and capacity to understand the nature of the wrongdoing (insanity, diminished capacity, intoxication), others appear as external effects that do not concern the defendant’s criminal capacity but their mens rea (mistake of fact, duress, coercion).

It should be noted that jurisdictions heavily disagree over which circumstances to accept as affecting the perpetrator’s criminal responsibility and what the effects of a partial or full excuse are. For example, diminished capacity is accepted as a partial defense in some US states but not in others. The effects of voluntary substance abuse also vary across civil- and common-law jurisdictions. Some of the most common examples of defenses that affect individual capacity are examined below.

3.2 Common defenses affecting criminal capacity

3.2.1 Insanity

3.2.1.1 Concept of insanity in criminal law

Insanity is a defense found in most criminal legal systems that results in a lack of criminal responsibility and, in most cases, compulsory treatment of the offender in a mental facility rather than imposing a criminal penalty in the traditional sense. However, the definition of insanity and the legal procedure used to prove its existence vary across different legal traditions. Another major distinction regarding insanity relates to its consequences.

It should be noted that the term “insanity” itself can be considered outdated and fails to encompass all kinds of mental disability, brain damage, and even conditions arising from neurodiversity, which can cause cognitive and volitional effects similar to those defined under various provisions. The terminology may be considered non-inclusive and discriminatory against neurodiverse persons [24]. Additionally, in cases where courts adhere to the letter of the law, their interpretation may prevent such individuals from successfully resorting to a defense in criminal matters.

A common point across different legal systems is that automatism caused by external forces and brain damage cannot be designated as insanity in criminal law. Automatism results in the lack of human action and would normally result in acquittal in contrast to insanity, which would generally lead to compulsory treatment [25, 26].

Insanity is understood to encompass organic and functional, permanent, transient, and intermittent effects that are in effect at the time of the act [6, 25]. As such, a “brief psychotic episode” that does not originate from an underlying mental disease may result in the exculpation of the defendant [26].

In any case of an insanity defense, there must be a causal link between the existing mental condition and the act committed by the defendant. The mere existence of a mental condition, however severe, does not exculpate the offender if the said condition did not contribute to the commission of the offense in trial. However, if the person is convicted of the crime and is unfit to be incarcerated due to their mental condition, alternatives to incarceration, including confinement in a mental institution, may be sought by criminal justice systems.

3.2.1.2 Various definitions and standards related to the insanity defense

In most civil-law countries such as Germany, Turkey, Italy, and Spain, insanity is mostly defined as being incapable of appreciating the unlawfulness of one’s actions or of acting in accordance with any such appreciation. In fact, the legal definitions found in the respective criminal codes of these countries (par. 20 German Criminal Code, art. 20/1 Spanish Criminal Code, art. 32 Turkish Criminal Code) are almost identical. This definition comprises two elements: cognitive and volitional [24, 27]. The lack of either element results in a successful insanity defense. Thus, both mental conditions that result in an inability to distinguish right from wrong and conditions that involve uncontrollable or irresistible impulses can result in a lack of capacity.

It should be noted that various civil-law countries adopt different determinations as to when the capacity is to be considered affected. As such, the Turkish provision speaks of a complete lack of cognitive ability (i.e., the perpetrator cannot comprehend the legal meaning or consequences of the act he or she has committed), while the perpetrator’s ability to control their behavior only needs to be significantly diminished [28]. The German provision (par. 20 German Criminal Code) includes the following list of mental conditions that qualify as a basis for the insanity defense: “a pathological mental disorder, a profound consciousness disorder, debility or any other serious mental abnormality” [6].

Other civil-law criminal legal systems, such as the Netherlands, refrain from legally defining mental illness and from specifying the types of mental conditions that would lead to an exclusion of criminal responsibility [29].

Common-law systems mostly derive their definition of the insanity defense from the M’Naghten standard, laid down by the UK House of Lords in the case of Daniel M’Naghten in 1843 [25, 30]. The standard, defined by Justice Tindal, is as follows: “To establish a defense on the ground of insanity, it must be proved that, at the time of the committing of the act, the party accused was laboring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing or if he did know it, that he did not know he was doing what was wrong” [31].

As can be seen, the original M’Naghten standard only mentions the cognitive element, stressing “not knowing the nature and quality of the act,” while it does not recognize the volitional element [32]. However, this standard has been revised in 1991 under the UK Criminal Procedure (Insanity and Unfitness to Plead) Act as to incorporate the volitional element and to replace the outdated terminology “disease of the mind” with any kind of “mental impairment,” which could encompass intellectual disability and personality disorders [33].

The M’Naghten standard was adopted by the US courts as well. However, the Model Penal Code (MPC), a non-binding legal text published in 1962 by the American Legal Institute to standardize US law, also introduced an alternative standard incorporating the volitional element. According to the MPC, the defendant is exculpated for reasons of “mental disease or defect” if, “…as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law” [34]. The second definition is understood to be broader: the MPC stresses the appreciation of wrongfulness rather than mere knowledge. Additionally, according to the MPC, a lack of “substantial capacity” is sufficient, as opposed to a complete lack of capacity. In 1984, a federal law entitled the Insanity Defense Reform Act (IDRA) was introduced following the acquittal of Hinckley, who attempted to assassinate President Ronald Reagan of the United States. This law restricted the use of the insanity defense by abolishing the volitional element of the definition and curtailed the possibility of other excuses based on “mental diseases or defects” (§17 IDRA) [27, 31]. It has been reported that in the wake of IDRA, courts in the majority of US states (approximately 30 states) still follow a version of M’Naghten rules, while approximately 14 states adopted the MPC standard. Five states abolished the defense, not allowing for insanity to exculpate the defendant unless the insanity caused a lack in the mens rea through a valid mistake of law [27, 35, 36].

In Canada, the M’Naghten standard was modified under Section 16 of the Criminal Code to include the lack of appreciation rather than mere knowledge of the nature and quality of the acts, in parallel with the US MPC. As a consequence, the inability to emotionally appreciate the effect of one’s actions, such as the possibility of them causing the death of another person, can be considered a valid defense of “mental disorder,” as called under Canadian law [37].

3.2.1.3 Burden of proof

The greatest distinction among major legal systems regarding insanity defense is undoubtedly related to the standard and burden of proof. Civil-law systems generally do not accept any suppositions of culpability and view the shift in the burden of proof to the defendant as a violation of the principle of culpability, as explained above. However, defenses in common-law countries tend to have standards of proof involving a reversal of the burden of proof. One major example of this is the insanity defense.

According to the M’Naghten rules mentioned above, any person is presumed to be sane. As such, “the accused must prove on the preponderance of probabilities first a defect of reason from a disease of the mind, and, secondly, as a consequence of such a defect, ignorance of the nature and quality (or the wrongfulness) of the acts” [25]. The standard of proof is lower than the one required to convict a person: it is based on the balance of probabilities rather than the “beyond reasonable doubt” standard. This standard requires that, other things being equal, the burden be placed on the party arguing for the improbable event [38]. The reason for this presumption of sanity is explained as that solely the accused holds the knowledge on the facts related to the nature of the insanity [39]. Although US courts uphold the constitutionality of this standard, it should be stressed that this presumption severely restricts the number of cases where insanity can be accepted as a valid excuse [38].

In many US states, such as New York, insanity defense is considered an affirmative defense, which means that the defendant bears the burden of proof that he or she was under an exculpating mental condition at the time of the act. However, it is still the prosecution that needs to prove mens rea, that is, intent, in a specific case [36].

In civil-law systems, the proof of insanity follows the general rules on the determination of the defendant’s guilt, and, according to the presumption of innocence, the defendant is considered innocent until proven guilty. Thus, the defendant cannot be considered under any burden of proving the existence of insanity [6, 27].

Since the determination of insanity mostly involves technical expertise, in most cases, forensic experts evaluate the mental status of a defendant, whereas the court is not necessarily bound by the outcome of the evaluation [6]. However, in most cases, the court will have to rely on the findings of the experts, which is a point of critique [27].

Under the Turkish criminal procedure system, the Council on Forensic Medicine (Adli Tıp Kurumu) is the official national body of expertise. In many situations, including the evaluation of mental status, an expert opinion from this institution is legally mandated. Under Article 74 of the Turkish Criminal Procedure Code (CPC), the defendant may be put under surveillance in a medical facility following expert opinion to determine whether insanity has affected their behavior during the act. This surveillance cannot extend beyond three months. However, the courts are free to disregard the outcome of the expertise on sufficient grounds [40].

3.2.2 Diminished responsibility

In the case of a mental disorder that does not affect the mental capacity of the offender to a degree to fully exculpate them, some legal systems recognize a partial excuse under the term “diminished responsibility.” However, the standards for allowing diminished responsibility as a valid defense and its legal consequences vary widely among different traditions.

German and Turkish criminal codes similarly define diminished responsibility. Under par. 21 of the German Criminal Code and art. 32/2 TCC, any mental condition that reduces but does not destroy a defendant’s cognitive and volitional capabilities during the act would result in this partial excuse. Legal consequences of diminished responsibility in civil law countries mostly include a mitigated sentence [41]. This mitigation may be accompanied by a special treatment program during incarceration; the possibility of applying special protective measures, including mandatory treatment, during the execution of the sentence; and a possible evaluation of the dangerousness toward society before being released from the correctional or medical facility [6].

According to art. 32/2 TCC, a defendant with diminished responsibility is still convicted to imprisonment for the crime they commit but to a reduced sentence. In addition, they may be subject to a measure of medical or psychological treatment in a medical facility that would partially or wholly replace the prison sentence.

In some common-law systems such as England and Australia, diminished responsibility is only accepted in cases of homicide and reduces the murder charge to manslaughter [25, 27, 39, 42]. The US, on the other hand, does not recognize diminished responsibility as a defense, but such conditions may fall under the sentencing judge’s discretion to apply a reduction [35].

In England and Wales, diminished responsibility is recognized as a special defense for the crime of homicide. According to Section 2(1) of the Homicide Act 1957: “Where a person kills or is party to the killing of another, he shall not be convicted of murder if he was suffering from such abnormality of mind (whether arising from a condition of arrested or retarded development of mind or any inherent causes or induced by disease or injury) as substantially impaired his mental responsibility for his acts and omissions in doing or being a party to the killing” [25].

As with the insanity defense, the defense of diminished responsibility places the burden of proof on the defendant in common-law systems that recognize it [25]. For civil-law countries, general principles on evidence and proof apply, as stated above, under the title of insanity.

3.2.3 Intoxication

A defendant who has acted under the influence of alcohol, drugs, or other substances may resort to a defense of intoxication. However, under most legal systems, voluntary intoxication rarely leads to a complete exculpation of the defendant and, in most cases, is not recognized as a defense at all. However, in most cases, involuntary intoxication is considered an excuse.

Intoxication is closely linked to the defense of temporary insanity. In fact, Turkish Criminal Code defines both conditions under the same article, art. 34 TCC. According to this provision, “a person who cannot appreciate the legal meaning and consequences of his or her actions or whose ability to conduct his or her actions according to this action has been substantially diminished as a result of a transitory effect, or due to a non-voluntary abuse of alcohol or narcotic drugs, shall not be punished.” The German Criminal Code does not define a separate defense of intoxication but considers it a special form of insanity [43].

Civil-law systems mostly accept this defense under the broader theory of actio libera in causa. According to this theory, the mens rea of the defendant who acted under voluntary self-intoxication is to be determined according to the point in time at which he or she took the substance, thus connecting the culpability of the defendant to their prior fault [26]. As a result, an offender who decides to intoxicate themselves in order to commit the crime without any moral inhibitions would be guilty of an intentional offense even if they did not possess the relevant will during the act itself. By contrast, a person who did not intend to commit a crime when he or she took the substance but should have known that the loss of control over his or her actions could result in a criminal act would be responsible for his or her negligence. Other types of mens rea, such as dolus eventualis or willful negligence, are also defined the same way [6].

An essential result of the doctrine of actio libera in causa is that the defendant may benefit from a complete exculpatory effect if, during a voluntary self-intoxication, he or she, as a reasonable agent, could not have predicted the acts he or she would later commit [29]. This might be the case if the defendant decides to take a drug in the privacy of his or her house but later is disturbed by a burglar, on whom the defendant applies excessive force as a result of the effects of intoxication. Most civil-law criminal legal systems would, in this example, conclude that no negligence was present for a lack of possibility in foreseeing the event, and therefore, voluntary self-intoxication provided an exculpation of the act itself. To avoid the possible loophole, the German legislator introduced a specific criminal offense penalizing the act of causing complete self-intoxication, as a result of which the defendant commits an unlawful act (par. 323a German Criminal Code) [43].

In contrast, the Turkish Criminal Code does not recognize the doctrine of actio libera in causa and introduces an irrebuttable presumption that any voluntary self-intoxication results in an intentional act, even if the act was not foreseen, or even foreseeable by the defendant at the time he or she took the substance that would lead to the loss of capacity (art. 34/2 TCC). However, this involuntariness is limited to the abuse of alcohol or drugs. In other words, any other kind of insanity that was affected by the culpable behavior of the offender would still be considered a valid defense under Turkish law. Even in the case of severe alcohol or drug addiction, when substance abuse cannot be seen as “voluntary,” pathological intoxication may provide a valid defense, albeit as insanity under art. 32 rather than intoxication under art. 34 TCC [44]. Similar consequences can be drawn in common-law systems [31].

In the US, it is accepted that any mental impairment “must have been brought about by circumstances beyond the control of the actor” [31]. Consequently, voluntary intoxication does not constitute a defense. However, in UK law, the effects of intoxication, voluntary or not, vary according to the mens rea required by the crime in question [25].

3.3 Infancy and age of criminal responsibility

3.3.1 Definition and rationale

Age of criminal responsibility refers to the minimum age at which a person can be held accountable for committing a criminal offense. In general, most legal systems recognize a minimum age for being considered a subject under criminal law capable of committing a crime; however, the specific age limit may vary significantly across different countries.

The 1989 UN Convention on the Rights of the Child specifically mentions the minimum age of responsibility under art. 40/3 as part of duties of States parties to the convention:

“States Parties shall seek to promote the establishment of laws, procedures, authorities and institutions specifically applicable to children alleged as, accused of, or recognized as having infringed the penal law, and, in particular:

(a) The establishment of a minimum age below which children shall be presumed not to have the capacity to infringe the penal law”.

The UN Committee on the Rights of the Children stated in 2007 that legislating the age of responsibility below the age of 12 was not “internationally acceptable” [45].

The age of responsibility is typically based on the assumption that children below a certain age lack the capacity to understand the nature and consequences of their actions. However, establishing a precise age threshold is challenging because of the inherent individual variability in cognitive and emotional development. Thus, an irrefutable legal presumption is set that excludes children below a certain age from responsibility, although in specific cases, the mental capacity of the child may indeed have reached the natural maturity that would, under normal circumstances, lead to liability. This presumption is independent of the nature of the crime committed [46].

3.3.2 Various approaches to the age of responsibility

In many legal systems, two different age limits are set: a minimum age that constitutes an irrefutable presumption and a higher age limit for the application of the so-called dolus incapax test, which denotes the evaluation of the natural maturity development of the child to determine his or her cognitive and volitional capacity regarding the particular crime committed. For example, in Turkey, the minimum age of responsibility is 12. Children below this limit are excluded from any type of criminal responsibility, whereas children between 12 and 15 years of age are subjected to the dolus incapax test conducted by experts. If, as a result of this test, they are found to be able to appreciate the legal meaning of their actions and conduct their behavior accordingly, they are subject to a criminal trial and may be convicted of a mitigated sentence. Otherwise, they are completely treated as children [28]. Children above the age of 15 but under 18 are considered juvenile offenders and subject to a criminal trial followed by a possible conviction. If a child’s mental development is impaired by any internal or external circumstance that prevents their cognitive or volitional abilities beyond the age of 15, they may be subject to the provisions of insanity. This distinction is criticized in Turkish law for not allowing mentally or developmentally challenged youth to be treated the same way as other children [44].

In Germany, the minimum age limit is 14 years, while the dolus incapax test is applied to all children between 14 and 18 years of age. Most European countries also have the 14-year limit with or without a dolus incapax test for older children [46].

The UK applies the youngest age of responsibility in Europe, 10, a situation that causes international criticism [45]. Until 1998, the dolus incapax test was applied to children between the ages of 10 and 14, whereas the burden of proof of lack of capacity was on the prosecution. However, in 1998, the government abolished the test through Section 34 of the Crime and Disorder Act 1998, resulting in all children above the age of 10 being criminally responsible. Reportedly, the main reason for this amendment was the killing of a 2-year-old boy by two 10-year-olds in 1993 [45].

It should be noted, however, that many common-law jurisdictions, particularly a large number of US states, do not recognize a statutory minimum age of responsibility [46].

3.3.3 Legal consequences of infancy

Children below the age of responsibility may be subject to special protective measures that aim to protect them from outside influences that could lead to criminal behavior or to remove them from a harmful environment. However, it should be noted that the process of determining such a measure lies normally outside of the rules of criminal procedure [46].

Under most legal systems, a distinct juvenile court structure and criminal procedure are provided for children above the age of criminal responsibility. In determining whether the child may be punished as an adult or whether they should be treated as a child, their mental capacity may be individually assessed by experts. In most cases, special protective measures may be applied in addition to any punishment, and any prison sentence they receive is subject to mitigation [47].

In many common-law systems, children tried by juvenile courts have the right to choose to be tried by a jury or to be subject to bench trial [48]. In civil-law countries, the trial is generally conducted in camera, closed to the public. The Turkish Criminal Procedure Code provides under art. 185 that all criminal trials against persons under the age of 18 must be conducted closed to the public, including the pronouncement of the judgment.

In many countries, juvenile judges and prosecutors are specifically trained in child psychology, and additional social workers, pedagogues, psychologists, and sociologists may be employed in the criminal justice system. An essential aspect of the juvenile criminal procedure is that the traumatization of the child is sought to be avoided by creating a trustful environment and by treating the child not as a criminal but as a victim of circumstances. In general, deprivation of liberty may only be applied as a last resort when it involves children. In addition, the child has the right to have a person of trust to be present during the proceedings. On 21.5.2016, the EU introduced Directive 2016/800 on procedural safeguards for children who are suspects or accused persons in criminal proceedings, which include many of the safeguards listed above.

In many legal systems, special provisions regarding recidivism and the protection of criminal records of children are introduced in order to protect them against the stigmatizing effects of a criminal conviction [47].

4. Conclusion

Our findings show that the definition of criminal responsibility and its role in criminal legal systems are consistent in that the concept of responsibility is based on the presumption of human agency and the ability to choose between what is legally right and wrong. If the criminal liability is determined solely according to the harm caused by the perpetrator, the punishment is conceived as disproportional and overly harsh. Thus, the concept of guilt based on the presumption of free will is needed to mitigate this outcome and to strike a balance between deterrence and resocialization.

Many legal systems recognize the principle of individual criminal responsibility and reject vicarious liability. However, they have strikingly different approaches regarding the role of culpability, the criminal liability of legal entities, and the burden of proof regarding personal guilt. Many legal systems, particularly those pertaining to the common-law tradition, acknowledge the existence of strict liability offenses, while civil-law systems require the existence of culpability and the corresponding mens rea as a general rule.

This discrepancy is even more prevalent for defenses, their role, and consequences in the criminal legal system. This discrepancy is partly explainable by the difference in legal traditions. Common-law systems tend to derive their definitions and legal categorization from a long-lasting series of precedents. This is the case in the definition of insanity and infancy, as well as the requirements about the proof of such conditions. These long-lasting precedents may be one reason why legislators and courts cannot easily develop new standards regarding these issues.

However, another major issue regarding the development of standards concerning capacity-related defenses is that the tendency of legislators to intervene with populistic and reactionary motives. In some situations, when the consequences of a lenient law disturbed the public sentiment of justice, the legislators in the US and the UK intervened with the existing legal status of perpetrators with restricted agency and changed the existing legal standards in a way to disallow the application of defenses under such circumstances. Such interventions invariably cause lasting effects that may affect greater injustice in the following years. However, since these eventual effects do not stir the public opinion to cause a comparable sense of urgency, the changes stay nevertheless in effect. This populism, while more visible in common-law systems, is prevalent throughout legal systems of the world, particularly within the last decades.

A third issue regarding the definition of the defenses like insanity, diminished responsibility, intoxication, and infancy that is common to all legal systems is that terminology, definitions, and consequences tend to be outdated in legal provisions. It is necessary that legislators and courts follow the scientific development in behavioral sciences more closely to adapt the legal standards to the existing scientific level. One major example of this is that insanity is regarded as a single monolithic cause affecting criminal responsibility, while neurodivergence as well as different brain-related syndromes are either not addressed at all or forced to fall under the same broader umbrella. This not only causes discriminatory practices in the criminal justice system but also results in a shortcoming of legal institutions for the needs of affected persons.

As a conclusion, criminal legal systems should aim to develop harmonized provisions regarding criminal responsibility based on scientific findings and standards rather than responding to conjunctural public sensation with populistic motives.