Mens rea
In criminal law, mens rea is the mental state of a defendant who is accused of committing a crime. In common law jurisdictions, most crimes require proof both of mens rea and actus reus before the defendant can be found guilty.
Introduction
The standard common law test of criminal liability is expressed in the Latin phrase actus reus non facit reum nisi mens sit rea, i.e. "the act is not culpable unless the mind is guilty". As a general rule, someone who acted without mental fault is not liable in criminal law. Exceptions are known as strict liability crimes. Moreover, when a person intends a harm, but as a result of bad aim or other cause the intent is transferred from an intended victim to an unintended victim, the case is considered to be a matter of transferred intent.The types of mental states that apply to crimes vary depending on whether a jurisdiction follows criminal law under the common law tradition or, within the United States, according to the Model Penal Code.
In civil law, it is usually not necessary to prove a subjective mental element to establish liability for breach of contract or tort, for example. But if a tort is intentionally committed or a contract is intentionally breached, such intent may increase the scope of liability and the damages payable to the plaintiff.
In some jurisdictions, the terms mens rea and actus reus have been replaced by alternative terminology.
Levels of ''mens rea'' within the United States
Under the tradition of common law, judges would often require a "bad state of mind" in addition to an action or omission to find a criminal guilty. Over time, culpable mental states became varied among different types of crimes. Such crimes and mental states might include, for example, "malice" for murder, "fraudulence" for fraud, "willfulness and corruption" for perjury, and so on. The crime of manslaughter, further, might not even require a "bad mind" but simply a "negligent" one. Regardless of how the requirements are categorized, the Supreme Court has explained mens rea requirements for crimes are "universal" and essential to "mature systems of law", even going so far as to say that this belief undergirds notions of free will and morality.Within the United States, there is no single encompassing criminal law. Criminal laws are passed and enforced by the states‚ or the federal government, but each of these criminal "codes" vary and may or may not draw from the same theoretical sources.
State criminal law
The vast majority of criminal prosecutions in the United States are carried out by the several states in accordance with the laws of the state in question. Historically, the states applied common law rules of mens rea similar to those extant in England, but over time American understandings of common law mens rea terms diverged from those of English law and from each other. Concepts like "general intent" and "specific intent" dominated classifications of mental states in state common law, but by the late 1950s to early 1960s, the common law of mens rea was widely acknowledged to be a slippery, vague, and confused mess. This was one of several factors that led to the development of the Model Penal Code. Nevertheless, states continue to use mental states beyond or besides those listed in the Model Penal Code.Supreme Court Justice Stephen Breyer described the distinction between the two systems in his dissent in Delling v. Idaho:
Federal criminal law
Since the federal government of the United States does not have a generalized police power like that of the states, the scope of its criminal statutes is necessarily circumscribed. Ordinary prosecutions are the province of the states, and only crimes connected to the constitutional powers may be pursued by the federal government. Nevertheless, the Supreme Court holds that required mens rea is an essential element of federal criminal offenses. Consequently, Title 18 of the United States Code does not use the aforementioned culpability scheme but relies instead on more traditional definitions of crimes taken from common law. For example, malice aforethought is used as a requirement for committing capital murder, and the Supreme Court has applied mental states such as "willfully."Model Penal Code
Because the landscape of criminal law varied from state to state, the American Law Institute declined to issue a restatement of criminal law in favor of a "model" code for states to issue new, standardized criminal law. This Model Penal Code was completed in 1962, and received praise from legal scholars for its reformulation of criminal law. Although not all states follow the criminal law as constructed within the MPC, over 34 states had adopted part or substantially all of the MPC as law by 1983. The federal government has not adopted the MPC, although it has attempted to do so for many decades.The formulation of mens rea set forth in the Model Penal Code has been highly influential throughout the United States in clarifying the discussion of the different modes of culpability since its publication. The following levels of mens rea are found in the MPC §2.02, and are considered by the United States Supreme Court to be the four states of mind that give rise to criminal liability:
- Negligently: a "reasonable person" ought to be aware of a "substantial and unjustifiable risk" that is a "gross deviation" from a normal standard of care.
- Recklessly: the actor "consciously disregards a substantial and unjustifiable risk" in "gross deviation" from a normal standard of care.
- Knowingly: the actor is "practically certain" that his conduct will lead to the result, or is aware to a high probability that his conduct is of a prohibited nature, or is aware to a high probability that the attendant circumstances exist.
- Purposefully: the actor consciously engages in conduct and "desires" the result. The Supreme Court has not found a large difference between purposeful and knowing conduct, not only in theory but also in application.
The MPC also recognizes culpability not because of a mental state, but for crimes that are legislatively proscribed due to the imposition of "absolute liability." Strict liability crimes will require evidence of such legislative intent, and courts seriously examine such evidence before assuming a crime permits strict liability rather than a mens rea.
- Strict liability: the actor engaged in conduct and his mental state is irrelevant. This mens rea may only be applied where the forbidden conduct is a mere violation, i.e. a civil infraction.
Differences between common law crimes and MPC crimes
| 18 U.S.C. §1111 | Texas Penal Code §19.02 |
| Murder is the unlawful killing of a human being with malice aforethought. | A person commits an offense if he: intentionally or knowingly causes the death of an individual. |
In the common law approach as under 18 U.S.C. §1111, the definition of murder includes an actus reus and a common law mens rea: malice aforethought. Modern criminal law approaches the analysis somewhat differently. Using a framework from the American Law Institute's Model Penal Code, homicide is a "results" offense in that it forbids any "purposeful" or "knowing" conduct that causes, and therefore results in, the death of another human being. "Purposeful" in this sense means the actor possessed a conscious purpose or objective that the result be achieved. "Knowing" means that the actor was aware or practically certain that a death would result, but had no purpose or desire for it to occur. By contrast with traditional common law, the Model Penal Code specifically distinguishes purpose and knowledge to avoid confusion regarding "intent" elements. Many states still adhere to older terminology, relying on the terms "intentional" to cover both types of mens rea: "purposeful" and "knowing".
Limits and criticisms of MPC ''mens rea''
Not all states have adopted the MPC, and for states that have, application of the Model Code varies. Despite its attempt to standardize criminal law, this variance has resulted in confusion and criticism. Some scholars have criticized the levels of culpability in the current Model Penal Code as insufficient or needing revision. Scholars' allegations include incoherency from conflicted philosophical commitments, or the federal governments' failure to explicitly adopt the Model Penal Code resulting in departure from common law precedents. Since the publication of the MPC, confusion has also occurred where norms towards crimes have also changed: especially regarding sexual crimes, hate crimes, drug crimes, and digital crimes. But while some scholarship argues that commitment to reforms gave way to "cynicism and fatigue," others argue the original commitment of the MPC to "imprisonment as a last result" should be preserved in potential revisions to the Code and criminal law.Rather than dwell on philosophical or normative arguments, some scholars have looked to evidence-based arguments to update the Code. In an empirical study, participants were presented with scenarios and asked to rate how deserving of punishment the scenario was. The results showed that participants' judgments matched up with the hierarchy of mens rea in the MPC, but also found that participants struggled most with "recklessness" scenarios. As a result, the study suggests revising the language of the categories.