Concept
The Act Requirement
Possession offenses
The Act Requirement
Under § 2.01 of the Model Penal Code, criminal liability must rest on conduct, and conduct for this purpose means a voluntary act or the omission of an act the person was physically capable of performing.1 The three subsections below take that baseline apart one piece at a time. The first states the voluntary-act rule and what makes an act voluntary. The second covers the bodily movements the Code removes from that category, among them reflexes, convulsions, and movements during sleep or unconsciousness. The third covers omissions, which support liability only when the offense itself makes the omission sufficient or the law otherwise imposes a duty to act.2
Each piece has its own reason. The voluntary-act requirement exists because punishment is meant to answer choices. A movement the person did not control, such as a spasm, cannot be deterred in advance, since the person could not have chosen otherwise, and condemning it would punish a happening rather than a decision. The limit on omissions has a different logic. At every moment each person is failing to do countless things, so if any failure to act counted, nearly everyone would be guilty of something at all times. Requiring a statute or an independent legal duty picks out the particular person whom the law has told to act, and that is what makes the failure blameworthy.
Possession sits awkwardly against both halves of this baseline. A possessor who is sitting still is making no bodily movement at the moment the state seeks to punish, so there is nothing to examine for voluntariness in the ordinary sense. Possession also does not fit comfortably as an omission, because no duty independent of the possession statute requires the possessor to dispose of the item. The only candidate for that duty is the statute whose conduct element is the very thing in question.
That gap is why the Code supplies a separate provision for possession, taken up after the three baseline rules are in place.
Voluntary Act Rule
Model Penal Code § 2.01(1) sets the first condition of criminal liability: a person is not guilty of an offense unless liability rests on conduct that includes a voluntary act, or on the omission to perform an act the person was physically capable of performing.4 The rule has two halves, and this subsection concerns the affirmative one. Its pivotal word is "act." The Code's general definitions treat an act as any bodily movement, whether voluntary or involuntary, which is why § 2.01 has to add the word voluntary. Without that qualifier, a muscle spasm would count as an act in the definitional sense and could carry a conviction.5
An act that can support liability is therefore a bodily movement that results from the person's will being exerted on the outside world.6 Two consequences follow from that definition. A thought, plan, or desire is never an act, however wicked, because nothing about it moves the body. Speech can be an act, because speaking is a bodily movement of the lips, tongue, and throat produced by choice, and that is why a statute can punish words without offending the requirement. The line the rule draws, then, runs between chosen movement and everything else.
The two scenes differ in one fact, whether the will produced a movement, and that fact decides the result. The requirement has several explanations, and they emphasize different things. The deterrence explanation observes that punishment works by giving people a reason to choose differently, so conduct a person cannot choose to perform or avoid cannot be deterred, and threatening it accomplishes nothing. The fairness explanation holds that it is unjust to blame someone who lacked the capacity to conform to the law.7 The Code's drafters added a third reason, that "the sense of personal security would be undermined in a society where such movement or inactivity could lead to formal social condemnation."8 Limiting conduct to bodily movement also keeps the criminal law out of the business of punishing bad thoughts, since a thought gives the state nothing it can observe or prove as a deed.
The omission half of the rule rests on the same logic. A failure to act reflects a choice only if the person could have acted, so the Code limits omission liability to acts the person was physically capable of performing. No one can fairly be condemned for failing to do the impossible. Which omissions can support liability at all depends on a further requirement, an express provision in the offense or a legal duty to act, taken up in its own subsection below. Possession raises the sharpest puzzle for the voluntary-act rule, because a possessor sitting still makes no movement at the moment of arrest. Section 2.01(4) answers by deeming possession an act when the possessor knowingly procured or received the thing, or was aware of controlling it long enough to have been able to end the possession.9 That provision works only because the baseline rule demands a voluntary act in the first place.
Involuntary Movements
The voluntary-act rule leaves one question open: which bodily movements count as voluntary? The Code's general definition treats an act as any bodily movement, so the word voluntary needs content, and § 2.01(2) supplies it by listing movements that are not voluntary acts.11 The list has four entries: a reflex or convulsion, a bodily movement during unconsciousness or sleep, conduct during hypnosis or resulting from hypnotic suggestion, and any other bodily movement that is not a product of the effort or determination of the actor, either conscious or habitual.12 The reason for the list is the reason behind the voluntary-act rule generally. A body that moves without being willed reflects no choice, and punishment cannot influence what was never chosen. Each entry describes a way in which a body can move without the person having directed it.
The first three entries are defined by the condition of the body or mind when the movement occurs. A reflex or convulsion is a movement the nervous system produces without any exercise of will. A pedestrian seized by an epileptic convulsion whose arm jerks back and strikes a bystander has committed no voluntary act, and the blow cannot support a conviction. Sleep and unconsciousness remove the will altogether, so a movement made in either state is excluded, although a defendant will be found to have acted unconsciously only in rare situations. Hypnosis works through the same gap. A person who carries out a hypnotic suggestion is following the hypnotist's direction, and the movement does not originate in the person's own determination.
The fourth entry is a catch-all for movements that are not the product of the actor's effort or determination, and its qualifier does the most work on an exam: the determination may be conscious or habitual.13 A movement that has become automatic through practice, such as tying a shoe or reaching for a light switch, still comes from the actor's own settled determination, so it remains a voluntary act. If habit counted as involuntary, the exclusion would swallow ordinary conduct, since most of what people do all day is practiced and unreflective. Students lose this issue when they treat automatic movements as involuntary merely because the actor did not stop to think. The test asks where the movement came from, and a shove from outside is a different source than a habit.
The two scenes differ in one respect, the source of the movement. In the first, the shove supplies it from outside the actor. In the second, habit is the actor's own determination settled into routine.14 Even a correctly excluded movement does not always end the inquiry, however, because the blameworthy choice may come earlier. A person who knew of a tendency toward seizures and unreasonably put himself where a seizure would likely harm others, as by driving a car, can be held liable on the strength of that earlier choice. The convulsion at the moment of the crash was involuntary, but the decision to drive, made while conscious and with knowledge of the risk, was a voluntary act that the conduct includes.
This list connects to possession offenses through the person who never learns of the item. A traveler whose suitcase a smuggler has secretly loaded with heroin may lift and carry the suitcase voluntarily, but no movement of the traveler's was directed to the drugs, and the traveler's will never reached them. That absence of choice is why § 2.01(4) deems possession an act only when the possessor knowingly procured or received the thing, or was aware of controlling it for a period long enough to terminate the possession.15 The unwitting possessor fits none of the four involuntary categories, because there is no movement toward the item to classify. The same lack of choice that excludes a convulsion leaves the unwitting possessor without an act.
Omission Liability
Section 2.01(1) allows liability to rest on the omission of an act the person was physically capable of performing, but § 2.01(3) narrows that permission considerably. Liability for an offense may not be based on an omission unaccompanied by action unless the omission is expressly made sufficient by the law defining the offense, or a duty to perform the omitted act is otherwise imposed by law.17 The restriction applies to pure inaction. A defendant whose own bodily movement caused the harm has engaged in conduct, so no search for a duty is needed. When the state's whole theory is that the defendant did nothing, the prosecution needs one of two routes, and omission liability analysis starts by asking which of them, if either, the facts supply.
The reason for the limit is that inaction, unlike action, has no natural boundary. At any moment each person is failing to do countless things that might help someone, so a rule punishing every failure to help whenever help was possible would reach nearly everyone. It would also leave the law with no answer to how far a stranger must go, or at what cost. A requirement of express statutory language or a legal duty supplies the missing boundary by tying blame to a specific obligation the law has placed on a specific person, which gives that person advance notice that failing to act is a crime. Moral expectation cannot do that work, because it has no edges: reasonable people disagree about when conscience demands a rescue, and a jury cannot be left to decide after the fact which ethical obligations were serious enough to punish. Two further conditions keep the duty fair. The person must have known the facts that called for action and must have been physically able to perform it, since a failure to act is a choice only when the person could perceive the need and could do the act.
The first route applies when the offense is itself written as a failure to act. Failing to file a required income tax return is the standard illustration: the statute names the failure as the forbidden conduct, so the omission is expressly made sufficient and the prosecution need look for no duty outside the offense.18 A statute commanding a class of people, such as clergy, to report known or suspected child abuse works the same way, because a failure to report then satisfies the conduct element of the reporting offense directly.19 The Code accepts this route without more because the legislature has already decided who must act and what the failure costs, so the duty and the crime arrive in a single provision.
The second route matters when the offense does not mention omission at all, as with homicide statutes that punish causing a death. There the prosecution must locate a duty to act somewhere else in the law.20 The recognized sources are a short list:
- A statute that imposes the duty, such as one requiring particular professionals to report suspected child abuse.21
- A contract, as when a nurse or lifeguard agrees to watch over another person.
- A status relationship, such as that between a parent and a minor child.
- A voluntary assumption of care, as when a person takes charge of someone who cannot protect themselves and thereby cuts off other help.
- The creation of peril, since a person who caused another's injury, even innocently, must summon aid.22
The creation-of-peril source shows how a duty can attach to a person who bears no blame for the original harm. A person who wounds another by accident is not guilty of the shooting, yet because he caused the injury he must summon medical aid at once, and if he does nothing and the victim dies, the failure is an omission that can support a homicide conviction.23 The duty explains the liability, and the innocent start of the episode does not remove it. The same source supplies the limit on the other side. Students lose this issue when they treat a moral obligation as a legal duty, because even a strong moral duty, such as an official's duty to report past abuse learned of years earlier, supports no criminal liability unless a statute or other source of law imposes it. The criminal law does not enforce every moral obligation.24
The two scenes differ in one fact, the existence of a legal duty. Knowledge and ability are identical in both, and the duty alone decides the result.
Even where a duty exists, the omission must be one the person could have avoided. Knowledge of the facts comes first, because a person cannot choose to leave undone something that person does not know needs doing. Physical capability comes second, and it is the condition § 2.01(1) already attaches to every omission, so the Code never punishes a failure that choosing differently could not have prevented.
Possession fits neither of these categories, and that gap is the reason § 2.01(4) exists. A possessor sitting still performs no bodily movement, so the voluntary-act half of the baseline has nothing to examine. Nor is the possessor failing to perform an act that a duty independent of the possession statute commands, because the only provision requiring the possessor to give up the item is the possession offense whose conduct element is in question. Treatments of the actus reus reflect this by listing possession as its own situation, separate from involuntary acts and from omissions. The Code answers the gap directly by deeming possession an act when the possessor knowingly procured or received the thing, or was aware of controlling it long enough to have been able to end the possession.25 That provision is the subject of the next part of this chapter.