The term, 'mens rea,' meaning 'a guilty mind; a guilty or wrongful purpose; a criminal intent,' is shorthand for a broad network of concepts encompassing much of the relationship between the individual and the criminal law. See Sanford H. Kadish & Stephen J. Schulhofer, Criminal Law and its Processes 217 (1989) ('A common usage is to express all . . . qualifications to liability in terms of the requirement of mens rea.'). These doctrines of criminal responsibility and the theories that support them are deeply rooted in our legal tradition as one of our first principles of law. To understand its import, it is necessary to unpeel the terse Latin. Western civilized nations have long looked to the wrongdoer's mind to determine both the propriety and the grading of punishment. See, e.g., Morissette v. United States, 342 U.S. 246, 250, n.4 96 L. Ed. 288, 72 S. Ct. 240 (1952) ('For a brief history and philosophy of this concept in Biblical, Greek, Roman, Continental and Anglo-American law, see Radin, Intent, Criminal, 8 Encyc. Soc. Sci. 126.'). 'For hundreds of years the books have repeated with unbroken cadence that Actus non facit reum nisi mens sit rea.' Francis Bowes Sayre, Mens Rea, 45 Harv. L. Rev. 974, 974 (1932) [hereinafter Sayre, Mens Rea]; see also Black's Law Dictionary 55 (4th ed. 1968) (defining the actus non rule: 'An act does not make [the doer of it] guilty, unless the mind be guilty; that is, unless the intent be criminal.'). This is the criminal law's mantra.
In his dialogues in Laws, Plato attempts to construct an ideal criminal code. He rejects the then-prevailing distinction between voluntary and involuntary acts in favor of gradation of crimes based upon levels of intent. A.E. Taylor, Introduction, in The Laws of Plato xlix-1 (A.E. Taylor trans., 1934). Plato's 'Visitor from Athens' explains: What the legislator has to ask himself is whether the agent of the beneficial or detrimental act is acting with a rightful spirit and in a rightful manner. . . . He must aim throughout his legislation at reconciling the minds of the authors and sufferers of the various forms of detriment by award of compensation, and converting their difference into friendship. . . . And then as to wrongful detriment -- or gain, either, in the case that a man should cause another to profit by a wrongful act -- such things, as we know, are maladies of the soul, and we must cure them whenever they are curable. . . . And so, if we can but bring a man to this -- to hatred of iniquity, and love of right or even acquiescence in right -- by acts we do or words we utter, through pleasure or through pain, through honour bestowed or disgrace inflicted, in a word, whatever the means we take, thus and only thus is the work of a perfect law effected. Id at 250-51. Plato then proceeds to lay out a nuanced criminal code that permits defenses based upon insanity, infancy and other forms of incapacity, that punishes premeditated murder more severely than homicide committed in the heat of passion and that absolves those who act unintentionally. Id. at 253-73 ('If a man unintentionally cause the death of a person . . . he shall, on accomplishing such purifications as may be directed by a law for these cases received from Delphi, be esteemed clear of pollution.').
The ancient English law tended towards strict liability for acts. But-for causation was considered the essential prerequisite to criminal fault. II Frederick Pollock & Frederic William Maitland, The History of English Law 470-71 (2d ed. 1968) ('If once it be granted that a man's death was caused by the act of another, then that other is liable, no matter what may have been his intentions or his motives.'); see also Sayre, Mens Rea, supra, at 975-80. The 'most primitive laws,' according to Pollock and Maitland, held men liable for 'acts' done by their slaves, beasts and even their possessions. II Pollock & Maitland, supra, at 472-73 ('If his sword kills, he will have great difficulty in swearing that he did nothing whereby the dead man was 'further from life or nearer to death.'').
Pollock and Maitland explain that the early law was hostile to the notion of examining an individual's mental state: It is hard for us to acquit the ancient law of that unreasoning instinct that impels the civilised man to kick, or consign to eternal perdition, the chair over which he has stumbled. But law which would not confess to sanctioning this instinct still finds grave difficulties in its way if it endeavors to detect and appreciate the psychical element in guilt and innocence. 'The thought of man shall not be tried, for the devil himself knoweth not the thought of man': thus at the end of the middle ages spoke Brian C.J. in words that might well be the motto for the early history of the criminal law. Id. at 474-75. While 'up to the twelfth century the conception of mens rea in anything like its modern sense was non-existent,' Sayre, Mens Rea, supra, at 981, it should be remembered that the very nature of most offenses rendered them unlikely or impossible of commission without some level of intent and that state of mind 'seems to have been a material factor, even from the very earliest of times, in determining the extent of punishment.' Id.
Toward the end of the Middle Ages, the modern focus on the criminal's state of mind gradually began to evolve. 'The history of the recognition of culpable states of mind should be viewed as a continuing process of self-civilization.' Paul H. Robinson, A Brief History of Distinctions in Criminal Culpability, 31 Hastings L.J. 815, 850 (1980) (describing evolution of culpability distinctions from ninth century to present). By the end of the twelfth century, the Roman law, with its concept of culpa, and the canon law, with it emphasis on moral guilt, began to influence the development of doctrines of culpability. Sayre, Mens Rea, supra, at 982-83. Holdsworth explains, As the idea grew up that to constitute a crime there must be some sort of a mens rea on the part of the accused, it came to look unjust to accuse a man of theft merely because he happened to be in possession of goods to which another had a better right. III A.W. Holdsworth, A History of English Law 322 (1927). The book of Leges of Henry I, which tends toward more primitive concepts of strict liability, recites in connection with the offense of perjury, 'reum non facit nisi mens rea.' Sayre, Mens Rea, supra, at 983.
It was inevitable that the development of the criminal law, based as it is upon general and evolving societal mores, would track the development of prevailing views about moral wrongdoing. 'The early felonies were roughly the external manifestations of the heinous sins of the day.' Id. at 989. The word 'felon' itself is a derivative of a Latin term meaning one who is 'full of bitterness or venom' and who is 'cruel, fierce, wicked, base.' II Pollock & Maitland, supra, at 465. 'The requirement of a guilty state of mind (at least for the more serious crimes) had been developed by the time of Coke.' Glanville Williams, Criminal Law: The General Part 30 (2d ed. 1961). Coke, writing in the seventeenth century, described the crime of treason as follows: So as there must be a compassing or imagination, for an act done per infatunium, without compassing, intent, or imagination, is not within this act, as it appeareth by the expressed words thereof. Et actus non facit reum, nisi mens sit rea. . . . This compassing, intent, or imagination, though secret, is to be tryed by the peers, and to be discovered by circumstances precedent, concomitant, and subsequent, with all endeavour evermore for the safety of the king. Edward Coke, Third Institute 6 (London, W. Clarke & Sons 1817). In discussing larceny and theft, he declared, First it must be felonious, id est, cum anima furandi, as hath been said. Actus non facit reum, nisi mens sit rea. And this intent to steale must be when it cometh to his hands or possessions: for if he hath the possession of it once lawfully, though he hath animum furandi afterward, and carrieth it away, it is no larceny. . . .Id. at 107.
Once the 'exceedingly vague' concept of moral blameworthiness, Sayre, Mens Rea, supra, at 994, was recognized the law embarked upon the long journey of refinement and development of culpability distinctions that continues to this day. Id. at 994-1004. Increasing precision in the law of excuses and defenses was partly a cause and partly an effect of the firmness with which the mens rea principle came to be held. VIII A.W. Holdsworth, supra, at 433. After the twelfth century, defenses such as insanity, infancy or compulsion began to be recognized as negativing guilt. Sayre, Mens Rea, supra, at 1004-06. Mistake of fact did not become a well-recognized defense until the seventeenth century. Id. at 1014; see also VIII A.W. Holdsworth, supra, at 434. Holdsworth, in a chapter covering the fourteenth and fifteenth centuries, writes, The law has left far behind old rules which look merely at the act and neglect the intent; but it has not therefore swallowed whole the canonist's theory that moral guilt should be chiefly regarded. A formed intent not manifested by any overt act, even a frustrated attempt, will not amount to a felony. II A.W. Holdsworth, supra, at 452.
By the time Blackstone came to write his Commentaries in the middle of the eighteenth century, he was able to summarize the English criminal law as follows: All the several pleas and excuses which protect the committer of a forbidden act from the punishment which is otherwise annexed thereto, may be reduced to this single consideration, the want or defect of will. An involuntary act, as it has no claim to merit, so neither can it induce any guilt: the concurrence of the will, when it has its choice either to do or to avoid the fact in question, being the only thing that renders human action either praiseworthy or culpable. Indeed, to make a complete crime cognizable by human laws, there must be both a will and an act. . . . As no temporal tribunal can search the heart, or fathom the intentions of the mind, otherwise then as they are demonstrated by outward actions, it therefore cannot punish for what it cannot know. . . . And, as a vicious will without a vicious act is no civil crime, so, on the other hand, an unwarrantable act without a vicious will is no crime at all. So that to constitute a crime against human laws, there must be, first, a vicious will; and, secondly, an unlawful act consequent upon such vicious will. II William Blackstone, Commentaries on the Laws of England *20-21 (emphasis in original).
Two general statements can be made with some confidence about the status of mens rea in the modern criminal law. First, 'when it comes to attaching a precise meaning to mens rea, courts and writers are in hopeless disagreement.' Sayre, Mens Rea, supra, at 974; see also Leo Katz, Bad Acts and Guilty Minds 165-209 (1987) (exploring, through hypotheticals, the complexity of the mens rea principle); Gary V. Dubin, Mens Rea Reconsidered: A Plea for a Due Process Concept of Criminal Responsibility, 18 Stan. L. Rev. 322, 325 (1966) ('In sharp contrast to its nearly defied legal status, [mens rea] has for centuries remained anomalously and bafflingly elusive.'). Second, mens rea in some form remains a defining and irreducible characteristic of the criminal law. Glanville Williams, one of this century's most astute commentators on the criminal law, put the matter succinctly: It may be said that any theory of criminal punishment leads to a requirement of some kind of mens rea.
The deterrent theory is workable only if the culprit has knowledge of the legal sanction; and if a man does not foresee the consequences of his act he cannot appreciate that punishment lies in store if he does it. The retributive theory presupposes moral guilt; incapacitation supposes social danger; and the reformation aim is out of place if the offender's sense of values is not warped. Glanville Williams, Criminal Law: The General Part 30 (2d ed. 1961); see also Herbert L. Packer, Mens Rea and the Supreme Court, 1962 Sup. Ct. Rev. 107, 109 (1962) (to punish without reference to the actor's state of mind has no deterrence value and cannot be justified on retributive grounds since the actor is not morally blameworthy). Stephen, in summarizing the development of the English law, captures the relationship between these two general observations: The maxim, 'Actus non facit reum nisi mens sit rea,' is sometimes said to be the fundamental maxim of the whole criminal law; but I think that, like many other Latin sentences supposed to form a part of the Roman law, the maxim not only looks more instructive than it really is, but suggests fallacies which it does not precisely state. . . . The truth is that the maxim about 'mens rea' means no more than that the definition of all or nearly all crimes contains not only an outward and visible element, but a mental element, varying according to the different nature of the different crimes. Sir James Fitzjames Stephen, A History of the Criminal Law of England 94-95 (1883); see also Glanville Williams, Criminal Law: The General Part 30 (2d ed. 1961) at 32-33 (recognizing that mens rea requirement has been modified where necessary, permitting liability based upon negligence and even ('a more dubious development') without regard to fault).
A host of other modern authorities have stated the importance of the mental element in crime, though describing and justifying it variously. Bentham's utilitarian theories portrayed culpability requirements as essential to ensuring the 'economy' of punishment. Proportionality and deterrence were, for Bentham, the most essential principles of the criminal law. 'Every particle of real punishment that is produced, more than what is necessary for the production of the requisite quantity of apparent punishment,' he wrote, 'is just so much misery run to waste.' Jeremy Bentham, Principles of Penal Law, in 1 The Works of Jeremy Bentham 398 (John Bowring ed., 1962).
In his utilitarian approach to punishment, Bentham sought to promote deterrence. To that end, a rational actor with full knowledge of the relevant facts was required. Punishment will be ineffective and, therefore, wasteful if the violation is of an ex post facto law or the actor does not otherwise have notice of the law, if the actor is insane, an infant or intoxicated, or if the actor labors under a mistake of fact or in response to duress or physical compulsion. Id. at 397.
Holmes also analyzed the problem of mens rea from a utilitarian perspective. For Holmes, though deterrence is the 'chief and only purpose of punishment,' Oliver Wendell Holmes, The Common Law 46 (1881), retribution is also a justifiable goal: It may be said, not only that the law does, but that it ought to, make the gratification of revenge an object. . . . The first requirement of a sound body of law is, that it should correspond with the actual feelings and demands of the community, whether right or wrong. If people would gratify the passion of revenge outside of the law, if the law did not help them, the law has no choice but to satisfy the craving itself, and thus avoid the greater evil of private retribution. Id. at 41-42. Both the deterrent and retributive objectives were justifiable, according to Holmes, because 'no society has ever admitted that it could not sacrifice individual welfare to its own existence.' Id. at 43. As with Bentham, even though there would be no moral objection to punishing the unwitting actor in order to improve society as a whole, some form of culpability is required to ensure the effectiveness of penal sanctions. '[A] law which punished conduct which would not be blameworthy in the average member of the community would be too severe for that community to bear.' Id. at 50. The most salient aspect of Holmes' analysis, however, is his ready admission of negligence as satisfying the mens rea principle. According to Holmes, the criminal law, like tort law, should serve to compel individuals to bring their conduct within the parameters of what society deems reasonable. Id. The test for culpability should be primarily an 'external' one and the mens rea requirement is satisfied as long as the actor is aware of circumstances 'in which [his or her acts] will probably cause some harm which the law seeks to prevent.' Id. at 75. Not only must the individual 'find out at his peril things which a reasonable and prudent man would have inferred from the things actually known,' id., but strict liability is also implicitly permissible on his account since there will be instances in which the individual 'must go even further, and, when he knows certain facts, must find out at his peril whether the other facts are present which would make the act criminal.' Id. In general, strict liability has been limited to civil cases.
Modern law has been reluctant to extend the concept to criminal malum in se offenses -- the category into which drug dealing has been placed, even if only recently, by our society and legislatures. While recognizing that 'legal history shows a continual movement back and forth between extreme solicitude for the general security and extreme solicitude for the individual life,' Roscoe Pound described the mens rea principle as fundamental: It remains true that our legal treatment of delinquents is not preventive but is punitive in its whole conception and administration. Historically, our substantive criminal law is based upon a theory of punishing the vicious will. It postulates a free agent confronted with a choice between doing right and doing wrong and choosing freely to do wrong. It assumes that the social interest in the general security and the social interest in the general morals are to be maintained by imposing upon him a penalty corresponding exactly to the gravity of his offense. It is enforced by an elaborate machinery of execution of the appointed sentence. Roscoe Pound, Introduction, in Francis Bowes Sayre, A Selection of Cases on Criminal Law xxxiv-xxxvii (1927). The leading modern texts have taught the importance of mens rea in the criminal law. See, e.g., Sanford H. Kadish & Stephen J. Schulhofer, Criminal Law and its Processes 217-18 (1989); Williams, supra, at 30-33.
In his classic treatise, Bishop reports, 'Prompting the act, there must be an evil intent. . . . An act and evil intent must combine to constitute a crime.' 1 Joel Prentiss Bishop, Bishop on Criminal Law §§ 205-06 (9th ed. 1923); see also Edwin R. Keedy, Ignorance and Mistake in the Criminal Law, 22 Harv. L. Rev. 75, 81 (1908) ('It is a fundamental principle of the criminal law, for which no authorities need be cited, that the doer of a criminal act shall not be punished unless he has a criminal mind.'). 'Neither in philosophical speculation, nor in religious or moral sentiment,' Bishop writes, 'would any people in any age allow that a man should be deemed guilty unless his mind was so.' 1 Bishop, supra, § 287. Bishop counsels vigilance against erosion of this principle: The calm judgment of mankind keeps this doctrine among its jewels. In times of excitement, when vengeance takes the place of justice, every guard around the innocent is cast down. But with the return of reason comes the consciousness that where the mind is pure, he who differs in act from his neighbors does not offend. Id. § 289. Jerome Hall, in his treatise, expresses a similar view: The distinctions concerning intention, recklessness and negligence . . . are warranted on ethical grounds. The relevant ethical principle expressed in terms of mens rea, that penal liability should be limited to voluntary (intentional or reckless) commission of harms forbidden by penal law, represents not only the perennial view of moral culpability, but also the plain man's morality. It is a necessary principle if punishment is to be distinguished from other sanctions. Jerome Hall, General Principles of Criminal Law 133-34 (2d ed. 1960).
The leading current treatise is in accord. See 1 Wayne R. LaFave & Austin W. Scott, Substantive Criminal Law 270 (1986) (A 'basic premise' of the criminal law 'is that conduct, to be criminal, must consist of something more than mere action . . . some sort of bad state of mind is required as well.'). Perhaps the most important modern work on criminal culpability is H.L.A. Hart's Punishment and Responsibility (1968). This is a landmark collection of essays that vigorously defend the mens rea principle. Proceeding from the premise that it is characteristic of our own and all advanced legal systems that the individual's liability to punishment, at any rate for serious crimes carrying severe penalties, is made by law to depend, among other things, on certain mental conditions, id. at 28, Hart seeks the philosophical source of the culpability requirement. He rejects Bentham's utilitarian justifications as inadequate. If deterrence were the only objective of the criminal law and sacrifice of the individual were not a concern, strict liability would be permissible since punishment of those 'who act unintentionally or in some other normally excusing manner may have a utilitarian value in its effect on others.' Id. at 20; see also id. at 42-43, 179. To the contrary, if strict liability is admitted, Hart says, it is done 'with the sense that some other principle has been overridden.' Id. at 20.
Holmes' theory of 'objective liability' also fails in Hart's view. Id. at 38. Holmes erroneously poses a choice between a system in which mental conditions are used only to find moral culpability and one in which mental conditions are not considered at all. Id.
Hart finds no such dilemma. 'There are independent reasons, apart from the question of moral guilt, why a legal system should require a voluntary act as a condition of responsibility.' Id. Hart distinguishes between two 'moral' questions. First is the question, for the consideration of the legislature, whether enforcement of a given law produces more good than evil. If good outweighs evil, then the law is morally permissible. Second is the question, for consideration at the judicial stage, whether the particular person accused should be excused on account of his or her mental condition because that person 'could not have helped' doing the act and, therefore, punishment would be unjust. Id. at 39. Hart characterizes this mens rea principle as follows: The need to inquire into the 'inner facts' is dictated not by the moral principle that only the doing of an immoral act may be legally punished, but by the moral principle that no one should be punished who could not help doing what he did. Id. (emphasis in original). The mens rea principle, for Hart, flows from our society's commitment to individual choice. '[W]e look on excusing conditions as something that protects the individual against the claims of the rest of society.' Id. at 44. The existence of the panoply of excuses and culpability requirements in the criminal law allows the individual to exercise choice with respect to violation of the law. Id. at 44-45. Hart summarizes his analysis as follows: On this view excusing conditions are accepted as something that may conflict with the social utility of the law's threats; they are regarded as of moral importance because they provide for all individuals alike the satisfactions of a choosing system. . . . In this way the criminal law respects the claims of the individual as such, or at least as a choosing being, and distributes its coercive sanctions in a way that reflects this respect for the individual. Id. at 49 (emphasis in original); see also Andrew Ashworth, Principles of Criminal Law 128-29 (1991) (contrasting deterrence-based utilitarian theories with 'liberal' theories, which 'regard respect for the autonomy of each individual citizen as capable of overriding general calculations of social utility').
Henry Hart's thoughtful analysis of the criminal law led him to a destination quite close to H.L.A. Hart's. For Henry Hart, it is not just the mens rea principle but the whole of the criminal law that reflects the primacy of individual freedom and the individual's relationship to the community as fundamental organizing principles of our society. He writes, Man realizes his potentialities most significantly . . . by making himself a functioning and participating member of his community, contributing to as well as drawing from it. What is crucial in this process is the enlargement of each individual's capacity for effectual and responsible decision. For it is only through personal, self-reliant participation, by trial and error, in the problems of existence, both personal and social, that the capacity to participate effectively can grow. Man learns wisdom in choosing by being confronted with choices and by being made aware that he must abide the consequences of his choice. . . . Seen in this light, the criminal law has an obviously significant and, indeed, a fundamental role to play in the effort to create a good society. For it is the criminal law which defines the minimum conditions of man's responsibility to his fellows and holds him to that responsibility. Henry M. Hart, Jr., The Aims of the Criminal Law, 23 Law & Contemp. Probs. 401, 410 (1958).
The conclusion that mens rea has a primacy in modern criminal law was central to the magisterial analysis of Professors Jerome Michael and Herbert Wechsler in their two-part work A Rationale of the Law of Homicide, 37 Colum. L. Rev. 701, 1261 (1937). This work and those already referred to were foundational in the approach taken by the American Law Institute's Model Penal Code (Official Draft and Rev. Comm. 1985) (the Code), for which Professor Wechsler was reporter.