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Inchoate offenses punish conduct directed toward crime before the intended harm is completed. The impossibility defense addresses a difficult question: should liability arise when completion was impossible from the outset?
Distinctions between legal impossibility, factual impossibility, and inherently ineffective means have shaped attempt law for generations. Their treatment varies across common-law doctrine and the Model Penal Code, often turning on the actor’s intent and perceived circumstances.
Why Impossibility Matters in Inchoate Offenses
Inchoate offenses punish conduct directed toward criminal harm before the intended offense is completed. Attempt, solicitation, and conspiracy law therefore must distinguish between dangerous intent and conduct that cannot, under the actual circumstances, produce the planned crime.
Impossibility matters because an actor may believe that a crime can be completed even when an unknown fact makes completion impossible. For example, a person may try to pick an empty pocket or shoot at an unoccupied bed, believing a victim is present.
The Impossibility defense addresses whether that failure should prevent criminal liability. Its treatment reflects competing concerns: limiting punishment for conduct that could not cause the intended harm while recognizing that culpable purpose and substantial steps may still create public danger.
Courts and statutes have not treated all forms of impossibility alike. The distinction between factual and legal impossibility has historically shaped attempt liability and remains necessary for analyzing inchoate offenses.
Defining the Impossibility Defense
The impossibility defense concerns situations in which a defendant intends to commit a crime and takes steps toward doing so, but completion is impossible under the actual circumstances. Its relevance arises mainly in prosecutions for criminal attempt.
Traditionally, courts distinguish legal impossibility from factual impossibility. Legal impossibility exists when the intended conduct would not constitute a crime, even if the defendant completed every act contemplated.
Factual impossibility occurs when the intended crime is unlawful, but an unknown fact prevents completion. A person who attempts to steal from an empty pocket, believing money is inside, faces factual rather than legal impossibility.
The distinction has not been applied uniformly across jurisdictions. Many modern statutes and the Model Penal Code focus on the defendant’s belief and purpose, limiting the availability of impossibility as a defense to attempt liability.
Legal impossibility
Legal impossibility arises when a defendant intends to commit an act believed to be criminal, but the completed act would not violate any criminal law. Traditionally, this form of impossibility could defeat an attempt charge.
- The defendant’s objective, if achieved exactly as intended, would remain lawful.
- The mistake concerns the legal status of the intended conduct, property, or circumstance.
- The defense differs from factual impossibility, where criminal conduct is intended but unknown facts prevent completion.
For example, a person who takes property believing it is stolen may not be guilty of attempting to receive stolen property if the property was not stolen. The intended transaction lacks an element required by the offense.
The scope of the Impossibility defense varies by jurisdiction. Many modern statutes, including approaches influenced by the Model Penal Code, restrict traditional legal-impossibility distinctions by focusing on the actor’s beliefs and purpose.
Factual impossibility
Factual impossibility arises when a defendant intends to commit a crime but cannot complete it because an unknown fact or circumstance makes success impossible. The actor’s criminal purpose and conduct remain central to the analysis.
Common examples include:
- Attempting to steal from an empty pocket or safe;
- Shooting into a bed believed to be occupied when it is empty;
- Trying to receive stolen property that is not, in fact, stolen.
In most modern jurisdictions, factual impossibility does not excuse an attempted crime. A person who takes a substantial step toward an offense may be liable even though completion was impossible under the actual circumstances.
The Impossibility defense is therefore generally unavailable where the intended conduct would have been criminal if the facts were as the defendant believed them to be. Factual impossibility differs from a claim that the contemplated conduct was not unlawful at all.
The Role of Impossibility in Attempt Liability
Attempt liability addresses conduct that has moved beyond preparation toward the commission of a crime, even when the intended offense is not completed. Impossibility becomes relevant when completion fails because of circumstances unknown to the actor.
The central question is whether a person who intends to commit a crime and takes a substantial step should escape liability merely because success was unattainable. Courts distinguish between factual and legal forms of impossibility when answering that question.
Under modern approaches, factual impossibility generally does not defeat an attempt charge. For example, a person who reaches into an empty pocket intending to steal may still be liable for attempted theft, despite the absence of property.
The Impossibility defense has its greatest relevance where the contemplated conduct, even if completed exactly as intended, would not constitute a crime. This distinction shapes the traditional limits of criminal attempt liability.
Legal Impossibility as a Traditional Defense
Legal impossibility traditionally barred attempt liability when the defendant’s intended conduct, even if completed exactly as planned, would not constitute a crime. The doctrine rests on the principle that criminal attempt requires an objective criminal offense to be possible under the law.
For example, a person who believes it is illegal to import an item that is actually lawful may take substantial steps to import it. Under the traditional legal impossibility rule, that person cannot be convicted of attempting a nonexistent crime.
Courts historically distinguished this situation from factual impossibility. Legal impossibility concerned the legal status of the intended act, while factual impossibility involved an actual crime that failed because of unknown circumstances, such as attempting to steal from an empty pocket.
The Impossibility defense based on legal impossibility has been narrowed or abolished in many jurisdictions, particularly those influenced by the Model Penal Code. Its continuing availability depends on the applicable statute and jurisdictional precedent.
Factual Impossibility and Criminal Attempts
Factual impossibility arises when a defendant intends to commit a crime and takes a substantial step toward it, but an unknown factual circumstance makes completion impossible. In most modern jurisdictions, it does not excuse an attempted offense.
A mistake about circumstances is a common form of factual impossibility. For example, a person who reaches into an empty pocket intending to steal a wallet may be guilty of attempted larceny, despite the absence of property to take.
Impossibility may also result from an unknown factual condition. A person who fires at an empty bed, believing the intended victim is asleep there, can be liable for attempted murder even though no victim was present.
Courts generally focus on the actor’s criminal intent and conduct rather than whether success was possible. The Impossibility defense is therefore usually unavailable where the intended crime would have occurred if the facts were as the defendant believed them to be.
Mistake about circumstances
A mistake about circumstances occurs when a defendant intends to commit a crime but is unaware that a factual condition makes completion impossible. The defendant’s criminal purpose remains directed toward conduct believed to be unlawful.
For example, a person who reaches into an empty pocket intending to steal a wallet may be guilty of attempted theft. The absence of property is an unknown factual circumstance, not a legal barrier to liability.
Likewise, someone who fires at a bed believing a victim is present may face attempt liability if the bed is empty. The intended harm failed because of facts outside the actor’s knowledge.
Under the modern approach, factual mistakes of this kind generally do not support an Impossibility defense. Courts focus on the defendant’s intent and the substantial steps taken toward the offense, rather than the accidental impossibility of success.
Failure caused by an unknown factual condition
A factual condition unknown to the defendant may prevent completion of the intended crime. The defendant’s conduct fails not because the law permits it, but because a real-world circumstance makes success impossible.
For example, a person may reach into an empty pocket intending to steal a wallet, or fire at a bed believing someone is present when it is vacant. In each case, the intended offense cannot be completed.
Such circumstances generally create factual, rather than legal, impossibility. Under modern attempt law, factual impossibility usually does not excuse conduct when the defendant had the required criminal intent and took a substantial step toward the offense.
The Impossibility defense is therefore often unavailable where failure results from an unknown factual condition. Courts commonly assess the defendant’s beliefs and actions as though the circumstances were as the defendant understood them to be.
Pure Legal Impossibility and Mistakes of Law
Pure legal impossibility arises when a defendant intends to perform conduct believed to be criminal, but the conduct is not prohibited by law. The intended act would remain lawful even if completed exactly as the defendant planned.
- A person may believe that possessing a particular object is illegal.
- If no statute actually prohibits possession of that object, no completed crime exists.
- Under the traditional rule, an attempt charge generally cannot rest on that mistaken belief.
This result reflects the principle that criminal liability requires an actual legal prohibition. A mistake about what the law forbids ordinarily does not transform lawful conduct into a criminal attempt, even when the actor has a blameworthy purpose.
Pure legal impossibility differs from factual impossibility. In factual impossibility, the intended conduct would be criminal if circumstances were as the actor believed; in pure legal impossibility, the conduct would be lawful under all circumstances described.
Hybrid Legal Impossibility in Criminal Law
Hybrid legal impossibility arises when a defendant’s intended conduct would be criminal under the facts as the defendant believes them, but is not criminal because of an unrecognized legal or factual circumstance. The category has historically been difficult to define consistently.
- A person may believe property is stolen and attempt to receive it.
- If the property is not legally “stolen,” traditional doctrine may characterize the situation as hybrid legal impossibility.
Courts have often treated this form of impossibility differently from factual impossibility. The distinction turns on whether the failure concerns an external fact, such as the absence of contraband, or the legal status attached to that fact.
The Impossibility defense based on hybrid legal impossibility has lost influence in many modern jurisdictions. Statutory approaches, particularly those influenced by the Model Penal Code, commonly focus on the actor’s purpose and the circumstances as the actor believed them to be.
Inherent Impossibility and Ineffective Means
Inherent impossibility arises when the means selected are so incapable of producing the intended criminal result that success is highly unlikely or practically impossible. It differs from ordinary factual impossibility because the method itself is fundamentally ineffective.
Examples may include attempting to kill another person through superstition, such as a curse or voodoo ritual, or using an innocuous substance believed to be poison. The actor may possess criminal intent, yet the chosen method cannot realistically cause the contemplated harm.
Historically, some courts treated inherently ineffective means as a basis for limiting attempt liability, particularly where the conduct posed no actual danger. Modern approaches often focus more heavily on the actor’s purpose and apparent conduct than on the effectiveness of the method.
Under the Model Penal Code, inherent impossibility generally does not eliminate liability, though a court may reduce or dismiss punishment where the conduct was so inherently unlikely to cause harm that neither the actor nor others presented a public danger.
The Model Penal Code Approach to Impossibility
The Model Penal Code largely rejects impossibility as a bar to attempt liability. Under MPC § 5.01, an actor may be guilty of attempt when the conduct would constitute a crime if the circumstances were as the actor believed them to be.
This approach focuses on the defendant’s purpose and perceived circumstances rather than whether completion was objectively possible. A person who tries to steal from an empty pocket, believing it contains a wallet, may therefore be liable for attempted theft.
The Model Penal Code approach to impossibility also covers many situations historically described as factual or hybrid legal impossibility. The central question is whether the intended conduct would have been criminal if the facts had been as the actor supposed.
The Code retains limited judicial discretion for inherently unlikely attempts. A court may dismiss a prosecution when the conduct is so inherently unlikely to result in a crime that neither the actor nor others require the deterrence provided by criminal conviction.
Liability based on the actor’s belief
Under the Model Penal Code, attempt liability generally depends on the circumstances as the actor believes them to be. A person may therefore be guilty of an attempt even when completing the intended crime was factually impossible.
This approach focuses on the defendant’s purpose and conduct rather than on an accidental obstacle unknown to the defendant. For example, a person who reaches into an empty pocket intending to steal a wallet may be liable for attempted theft.
The rule rejects factual impossibility as a complete bar where the actor would have committed an offense if the facts were as believed. The Impossibility defense is therefore substantially narrowed under the Model Penal Code.
The actor’s mistaken understanding must concern circumstances, not merely a belief that lawful conduct is criminal. A mistake about the law does not ordinarily create attempt liability when the conduct, as the actor believes it occurred, would still be lawful.
Judicial discretion for inherently unlikely harm
Under the Model Penal Code, an actor may still be guilty of an attempt even when the intended crime was impossible to complete under the circumstances as the actor believed them to be.
The Code nevertheless permits judicial discretion where the conduct is so inherently unlikely to cause or culminate in harm that punishment is unwarranted. A court may dismiss the prosecution or reduce the grade of the offense.
Relevant considerations may include:
- The extreme ineffectiveness of the method used
- The absence of a realistic danger to any person or property
- Whether the conduct demonstrates a genuine criminal threat
This limited safety valve prevents the Impossibility defense from becoming overly broad while allowing courts to distinguish dangerous attempted crimes from irrational or plainly harmless efforts.
Common-Law Approaches to the Impossibility Defense
At common law, courts traditionally distinguished legal impossibility from factual impossibility when deciding attempt liability. Legal impossibility was generally recognized as a defense because the defendant’s intended conduct, even if completed, would not constitute a crime.
Factual impossibility usually did not excuse an attempted offense. A person who tried to steal from an empty pocket, for example, could be liable because stealing would have been criminal had the expected property been present.
Courts often struggled with cases involving mixed mistakes of fact and law, sometimes described as hybrid legal impossibility. The distinction produced inconsistent results because similar conduct could be classified differently depending on how the court characterized the mistake.
Modern common-law jurisdictions vary in their treatment of the Impossibility defense. Many have narrowed or rejected legal-impossibility distinctions through statutes or judicial decisions, focusing instead on the defendant’s intent and conduct toward committing the intended crime.
Impossibility in Solicitation and Conspiracy Offenses
Impossibility generally does not excuse solicitation when the defendant intentionally encourages another person to commit a crime. The offense is complete upon the request or inducement, even if the solicited person refuses, is unable to act, or is an undercover officer.
For example, a person who asks an undercover officer to commit murder may be guilty of solicitation despite the officer’s lack of criminal intent. The defendant’s purpose to promote the crime, rather than the practical likelihood of its completion, is ordinarily controlling.
Conspiracy raises different issues because traditional common law required a genuine agreement between at least two culpable parties. Under that bilateral approach, an agreement with an undercover officer or feigned participant cannot create a conspiracy.
Many modern statutes and the Model Penal Code use a unilateral approach. They permit conspiracy liability when the accused believes an agreement exists, even though the supposed co-conspirator lacks criminal intent. In this setting, the Impossibility defense has limited force.
Illustrative Examples of Impossibility in Attempt Cases
A person who reaches into an empty pocket intending to steal a wallet may still be guilty of attempted larceny. The intended theft fails because of an unknown factual condition: no wallet is present.
Similarly, firing a gun into an empty bed while believing the intended victim is asleep can support an attempted homicide charge. The victim’s absence makes completion impossible, but the actor’s intent and conduct remain dangerous.
Attempting to buy stolen property from an undercover officer may also create liability where the goods are not actually stolen. Under many modern statutes and the Model Penal Code, this factual or hybrid impossibility does not excuse the attempt.
By contrast, a person who seeks to engage in conduct mistakenly believed to be criminal, when the conduct is not prohibited at all, may raise legal impossibility. The availability of an Impossibility defense depends on the jurisdiction’s statutory rules and common-law doctrine.
Evaluating an Impossibility Defense in Practice
Courts evaluate an impossibility defense by identifying the charged inchoate offense, the defendant’s intent, and the conduct undertaken toward completion. The governing jurisdiction matters because common-law rules and Model Penal Code provisions may produce different outcomes.
The analysis separates factual barriers from legal barriers. If a defendant tries to steal from an empty pocket, factual impossibility generally does not defeat attempt liability because the intended conduct would have been criminal if the circumstances were as believed.
A claimed legal impossibility requires closer examination. A defense may be available where the intended acts would not constitute a crime even if completed, though many jurisdictions limit or reject this distinction, particularly for hybrid situations.
Counsel should examine statutory language, controlling appellate decisions, police conduct, and evidence of the defendant’s belief. In sting operations, the absence of an actual victim, contraband, or criminal opportunity often does not bar liability where the defendant intended an offense and took a substantial step.