Table of Contents
Impossibility in Criminal Attempts
One of the most interesting questions in criminal law arises when a person tries to commit a crime that, unknown to the person, cannot actually be completed.
Imagine someone intends to steal a wallet from another person’s pocket and reaches into the pocket—but the pocket is empty.
Or imagine someone intends to kill a person by putting what they believe is poison into the victim’s drink, but the substance is actually harmless.
Or suppose someone fires a gun at a person intending to kill them, but the gun is unloaded.
Has a crime been attempted?
The answer is not simply yes or no. Criminal law distinguishes between different forms of impossibility, and jurisdictions have developed different approaches to determining whether impossibility defeats attempt liability.
The central question is often this:
Should a person escape criminal responsibility for an attempt merely because circumstances unknown to them made the intended crime impossible to complete?
Modern attempt law generally focuses heavily on the defendant’s criminal intent and conduct, rather than simply asking whether successful completion was objectively possible.
Cornell Legal Information Institute — Attempt
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What Is Impossibility?
Impossibility in criminal attempts arises when the defendant intends to commit a crime and takes steps toward committing it, but the intended offense cannot actually be completed under the circumstances.
The impossibility may result from:
- an unknown factual circumstance;
- the absence of the intended victim or property;
- the nature of the object involved;
- the means selected by the defendant;
- a misunderstanding of the law;
- or some other circumstance preventing completion.
The important distinction is between:
“The defendant failed.”
and
“The defendant could never have succeeded under the circumstances.”
An ordinary failed attempt might have been capable of succeeding.
An impossible attempt may have been incapable of succeeding from the beginning.
Why Does Impossibility Matter?
The doctrine creates a tension between two ways of thinking about criminal responsibility.
One approach focuses on objective harm.
If the crime could never have happened, perhaps the defendant should not be guilty of attempting it because no actual criminal harm was possible.
The other approach focuses on criminal intent and dangerous conduct.
If the defendant intended to commit a crime and deliberately took substantial steps toward doing so, the fact that circumstances unknown to the defendant prevented success may not make the conduct less blameworthy.
Consider two people.
Alex points a loaded gun at a victim and pulls the trigger, but the victim moves at the last moment.
Beth points what she believes is a loaded gun at the victim and pulls the trigger, but unbeknownst to Beth, the gun is unloaded.
Both may demonstrate essentially the same criminal purpose and similar conduct.
The fact that Beth’s weapon could never have fired raises the impossibility issue.
Factual Impossibility
Factual impossibility occurs when the defendant intends to commit a crime, but an unknown factual circumstance makes completion impossible.
This is the classic example:
A person reaches into another person’s empty pocket intending to steal a wallet.
The defendant believes the wallet is there.
It is not.
The theft cannot be completed because the property does not exist in the expected location.
Another example:
A defendant intends to kill a person by shooting them while they sleep.
The defendant enters the bedroom, aims at the bed, and fires.
The defendant does not know that the victim left the room minutes earlier.
The intended killing cannot occur because the victim is not there.
In many jurisdictions, factual impossibility does not necessarily defeat attempt liability.
The defendant’s criminal purpose and conduct may be sufficient even though an unknown circumstance made successful completion impossible.
The Empty-Pocket Example
The empty-pocket example illustrates the principle particularly well.
Suppose Daniel sees Sarah carrying what appears to be a wallet.
Daniel decides to steal it.
He follows Sarah, approaches her, reaches into her pocket, and discovers that the pocket is empty.
Daniel intended to steal property.
He took conduct directed toward accomplishing that objective.
The fact that Sarah had no wallet does not necessarily transform Daniel’s conduct into something innocent.
The law may conclude that Daniel attempted theft even though the theft could never actually have been completed.
The precise result depends on the jurisdiction and statutory language.
Factual Impossibility vs. Mere Failure
It is important not to confuse impossibility with ordinary failure.
Suppose Daniel attempts to steal a wallet from Sarah but Sarah feels his hand and pulls away.
The theft was possible.
Daniel simply failed.
Now suppose Sarah’s pocket was empty from the beginning.
The theft was impossible under the actual circumstances.
Both situations may nevertheless constitute attempted theft.
The difference is:
Failure: the crime could have succeeded but did not.
Factual impossibility: the crime could not have succeeded because of an unknown factual circumstance.
Modern attempt law often does not treat that distinction as decisive.
Legal Impossibility
Legal impossibility is more complicated.
Legal impossibility traditionally arises when the defendant’s conduct, even if completed exactly as intended, would not constitute a crime because the defendant’s understanding of the law is incorrect.
For example, suppose a person believes that possessing a particular object is illegal when the law actually permits possession.
The person deliberately engages in the conduct believing they are committing a crime.
The question becomes whether the person can be guilty of attempting to commit an offense that does not legally exist under those circumstances.
Traditionally, legal impossibility was sometimes recognized as a defense to attempt.
Modern law, however, has narrowed the distinction in many jurisdictions.
The exact statutory language and jurisdiction therefore matter greatly.
Pure Legal Impossibility
The clearest case of legal impossibility occurs when the defendant’s intended conduct would not constitute a crime even if everything happened exactly as the defendant intended.
Suppose a person believes it is a crime to sell a particular lawful object.
The person intends to commit this supposed offense and takes every step necessary to complete the transaction.
If the conduct is not criminal under the applicable law, the defendant ordinarily cannot simply create a crime by mistakenly believing that the law prohibits it.
Criminal liability must rest on an actual legal prohibition.
This reflects the principle of legality: conduct cannot ordinarily be criminal merely because a person believes it is criminal.
Cornell Legal Information Institute — Legality
Factual Impossibility and Legal Impossibility Compared
| Factual Impossibility | Legal Impossibility |
|---|---|
| The intended crime is legally recognized | The intended conduct may not actually constitute a crime |
| An external factual circumstance prevents completion | The defendant misunderstands the legal status of the conduct |
| Example: empty pocket | Example: believing lawful conduct is criminal |
| Often does not defeat attempt | May defeat attempt depending on the jurisdiction |
| Focuses on circumstances | Focuses on the legal definition of the offense |
The distinction is useful, but modern attempt doctrine does not always treat these categories as cleanly as traditional common-law terminology suggests.
Factual Impossibility Usually Does Not Save the Defendant
The modern approach often asks what the defendant intended to do and actually did, rather than giving decisive weight to whether success was objectively possible.
Consider three examples.
Example 1: Empty Safe
A burglar breaks into a safe intending to steal $100,000.
The safe contains nothing.
The burglar may still be guilty of attempted theft.
Example 2: Unloaded Gun
A defendant believes a gun is loaded, points it at the intended victim, and pulls the trigger.
The gun is unloaded.
The defendant may still face liability for attempted murder if the jurisdiction’s attempt doctrine recognizes this conduct as sufficient and the required intent is established.
Example 3: Harmless Substance
A defendant believes a substance is lethal poison and puts it into the victim’s drink intending to kill.
The substance is harmless.
The defendant may still be guilty of attempted murder.
In each case, the defendant’s criminal objective was frustrated by circumstances outside the defendant’s knowledge or control.
The Defendant’s Perspective
One important way of understanding impossibility is to ask:
What did the defendant believe was happening?
Suppose a defendant reaches into a pocket believing a wallet is there.
From the defendant’s perspective, the conduct is part of an attempt to steal.
The defendant does not know that the pocket is empty.
Similarly, someone who fires an unloaded weapon believing it to be loaded may have the same homicidal purpose as someone whose weapon happens to be loaded.
This perspective helps explain why modern attempt law frequently emphasizes culpable intent plus sufficiently advanced conduct.
The Object of the Crime
Impossibility can arise because the object of the intended offense does not exist or is not present.
Examples include:
- attempting to steal property that is not there;
- attempting to receive stolen property that is not actually stolen;
- attempting to damage property that has already been destroyed;
- attempting to kill someone who is not present;
- attempting to obtain information that does not exist.
The legal analysis depends on the elements of the particular offense.
The prosecution must still prove that the defendant’s conduct satisfies the applicable attempt statute.
Impossibility and Attempted Murder
Attempted murder is one of the clearest contexts in which impossibility becomes important.
Suppose a defendant intends to kill Victor.
The defendant shoots at Victor but misses.
This is an ordinary failed attempt.
Now suppose the defendant shoots into Victor’s bedroom believing Victor is asleep inside, but Victor has secretly left.
The intended killing was factually impossible.
Nevertheless, the defendant may have committed attempted murder because the defendant possessed the necessary intent and took conduct sufficiently directed toward killing Victor.
The impossibility of success does not necessarily eliminate the criminality of the attempt.
Impossibility and Attempted Theft
The same reasoning can apply to theft.
Suppose a person reaches into another person’s bag intending to steal a laptop.
The bag is empty.
Or the person opens a safe intending to steal money but discovers that the safe contains nothing.
The defendant may have completed the conduct necessary for an attempt even though there was no property available to steal.
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The critical question is whether the jurisdiction treats the conduct and intent as sufficient for attempt liability.
Impossibility and Attempted Burglary
Consider a defendant who intends to burglarize a house.
The defendant believes the house is occupied and enters intending to steal.
Unknown to the defendant, the building has already been completely emptied.
The defendant may still be guilty of attempted burglary or another offense, depending on the jurisdiction and the elements of the offense.
Again, impossibility does not necessarily make the conduct legally irrelevant.
Impossibility and Mistake of Fact
Impossibility often overlaps with mistake of fact.
The defendant misunderstands some factual circumstance.
For example:
- believing a wallet is in a pocket when it is not;
- believing a person is present when they are not;
- believing a substance is poisonous when it is harmless;
- believing property is valuable when it has no value.
The mistake may make the intended crime impossible.
But the mistake does not necessarily eliminate the defendant’s criminal intent.
In fact, the defendant’s mistaken belief may demonstrate precisely what the defendant intended to accomplish.
Impossibility and Mistake of Law
Mistake of law is different.
The defendant misunderstands what the law prohibits.
For example, a person may believe that certain conduct constitutes a crime when it does not.
Criminal law generally does not permit a person to manufacture criminal liability merely through a mistaken belief about what conduct is illegal.
This is one reason legal impossibility has traditionally been treated differently from factual impossibility.
The Model Penal Code Approach
The Model Penal Code generally avoids making factual impossibility a broad defense to attempt.
Its attempt provisions focus on the defendant’s purposeful conduct and whether the defendant takes a substantial step strongly corroborating the criminal purpose.
This shifts attention away from the question:
“Could the crime objectively have succeeded?”
and toward:
“Did the defendant purposefully engage in conduct strongly corroborating the criminal objective?”
Cornell Legal Information Institute — Model Penal Code
This approach makes the doctrine more consistent with the broader philosophy of modern attempt law.
The Substantial-Step Approach and Impossibility
Under a substantial-step approach, the prosecution may establish attempt without proving that completion was objectively possible.
The defendant must have the required criminal purpose and take a substantial step toward the offense.
Examples of potentially significant conduct can include:
- lying in wait for a victim;
- reconnoitering a crime scene;
- possessing specially designed materials;
- enticing the intended victim to a particular location;
- beginning execution of the planned offense.
The impossibility of completion does not automatically erase the significance of those acts.
The Common-Law Debate
Historically, courts struggled with the distinction between factual and legal impossibility.
One traditional formulation was:
Factual impossibility is generally not a defense.
Legal impossibility may be a defense.
The problem was that the boundary between the two could become extremely artificial.
Consider a person who believes that an object is stolen and attempts to receive it.
If the object is actually not stolen, is this:
- factual impossibility because the object was not stolen?
- legal impossibility because receiving non-stolen property is not the intended crime?
- or attempted conduct based on the defendant’s mistaken belief?
Different courts and legal systems have approached such questions differently.
Modern statutes often provide more direct rules than traditional common-law terminology.
The “Impossible Crime” Problem
Impossibility raises an important philosophical question.
Suppose two defendants demonstrate identical criminal intent and take identical actions.
The only difference is an external fact:
- Defendant A’s victim is present.
- Defendant B’s victim is absent.
Should Defendant B receive substantially less criminal responsibility simply because circumstances prevented the crime from being possible?
The law of attempt often answers:
Not necessarily.
The reason is that criminal responsibility can be based on the defendant’s culpable conduct and purpose rather than solely on the amount of harm ultimately produced.
Impossibility Does Not Eliminate Every Requirement of Attempt
It is important not to go too far.
The fact that factual impossibility is generally not a defense does not mean that every impossible criminal plan constitutes an attempt.
The prosecution must still establish the required elements.
Depending on the jurisdiction, this may require proof of:
- the necessary criminal intent;
- conduct beyond mere preparation;
- a substantial step or other required act;
- a sufficiently specific target offense;
- and any additional statutory requirements.
A person cannot simply say:
“I wanted to commit a crime, but it was impossible.”
The prosecution still has to prove an actual attempt under the applicable law.
Impossibility and Abandonment
Impossibility can also intersect with abandonment.
Suppose a person begins carrying out a criminal plan but later voluntarily abandons it.
The legal consequences depend on:
- when the abandonment occurred;
- whether an attempt had already been completed;
- whether the jurisdiction recognizes abandonment as a defense;
- and whether the abandonment was voluntary.
The fact that completion later became impossible is a different issue from voluntary abandonment.
The two should not be confused.
Impossibility and Police Intervention
Police intervention can produce a superficially similar situation.
Suppose an undercover officer poses as a buyer.
The defendant intends to sell illegal drugs and takes substantial steps toward completing the transaction.
The transaction cannot actually be completed because the buyer is an undercover officer and no genuine criminal transaction can occur in the expected way.
Depending on the offense and jurisdiction, impossibility doctrines and law enforcement intervention may become relevant.
But the defendant’s conduct can still demonstrate a completed criminal attempt even though the planned transaction was disrupted by police.
Impossibility and Mens Rea
Impossibility highlights the importance of mens rea.
The defendant may be morally and legally blameworthy because the defendant intended to produce a prohibited result.
The fact that the result could not occur does not necessarily eliminate that mental state.
For example:
“I intended to kill him, but I did not know he was already dead.”
The defendant’s statement may actually demonstrate the required intent for an attempt, although the precise offense and result depend on the jurisdiction.
The impossible circumstance does not necessarily erase the defendant’s purpose.
Impossibility and the Principle of Legality
At the same time, attempt law must respect the principle of legality.
The state cannot punish someone simply because the person has a bad intention.
There must be a legally defined offense and legally sufficient conduct.
This creates an important boundary:
Factual impossibility may not defeat an attempt.
But the absence of an actual criminal prohibition cannot ordinarily be replaced by the defendant’s mistaken belief that conduct is criminal.
The principle of legality therefore limits how far attempt doctrine can go.
A Practical Framework for Analyzing Impossibility
When confronted with an impossible attempt, ask the following questions.
1. What crime did the defendant intend to commit?
Identify the target offense precisely.
2. What mental state did the defendant possess?
Determine whether the defendant had the required intent or purpose.
3. What made completion impossible?
Was the problem:
- a missing object?
- an absent victim?
- an ineffective weapon?
- a harmless substance?
- a mistaken factual assumption?
- or a misunderstanding of the law?
4. Was the impossibility factual or legal?
This distinction remains useful even though modern law may treat the categories differently.
5. What conduct did the defendant actually perform?
Determine whether the defendant crossed the preparation-attempt boundary.
6. What attempt test does the jurisdiction use?
Possible approaches include proximity, unequivocality, dangerous proximity, or substantial step.
7. Does the impossibility doctrine apply under that jurisdiction’s law?
The answer cannot safely be assumed from general common-law terminology.
8. Was the intended crime legally recognized?
If the defendant merely believed lawful conduct was criminal, legality may prevent attempt liability.
9. Was the defendant voluntarily abandoning the plan?
If so, analyze abandonment separately.
10. Did the defendant commit another offense?
Even if attempt liability fails, other completed offenses may exist.
Common Mistakes
Mistake 1: Assuming impossibility always defeats attempt
It usually does not follow automatically.
Mistake 2: Treating factual and legal impossibility as identical
They have traditionally been distinguished and may receive different treatment.
Mistake 3: Assuming intent alone creates attempt liability
The defendant must generally also take legally sufficient conduct.
Mistake 4: Assuming an impossible crime is always harmless
A defendant may demonstrate serious criminal purpose and take substantial steps toward execution even though circumstances prevent completion.
Mistake 5: Ignoring the jurisdiction
Attempt law varies significantly among jurisdictions.
Mistake 6: Confusing impossibility with abandonment
A crime being impossible is not the same thing as the defendant voluntarily abandoning it.
Mistake 7: Forgetting legality
A person cannot ordinarily create a crime simply by mistakenly believing that lawful conduct is prohibited.
Key Takeaways
- Impossibility arises when an intended crime cannot be completed under the actual circumstances.
- Factual impossibility commonly involves an unknown circumstance that prevents completion.
- Examples include an empty pocket, an absent victim, or an unloaded weapon.
- Factual impossibility generally does not automatically defeat attempt liability.
- Legal impossibility concerns situations where the intended conduct would not constitute the crime even if completed.
- Traditional law often treated legal impossibility differently from factual impossibility.
- Modern attempt doctrines, particularly substantial-step approaches, often focus on criminal purpose and conduct rather than objective possibility.
- The defendant must still satisfy the applicable elements of attempt.
- Impossibility does not eliminate the principle of legality.
- The exact result depends on the jurisdiction and the statute defining attempt.
Frequently Asked Questions
Can you be guilty of attempting a crime that was impossible to complete?
Yes, potentially. Factual impossibility generally does not automatically defeat attempt liability when the defendant possessed the required intent and engaged in sufficiently advanced conduct.
What is an example of factual impossibility?
A person reaches into a pocket intending to steal a wallet, but the pocket is empty. The intended theft cannot be completed, but the conduct may still constitute attempted theft.
What is an example of legal impossibility?
A person intentionally performs conduct believing it is criminal when the conduct is actually lawful. Because the supposed offense does not legally exist, the defendant may not be guilty of attempting it.
Is an unloaded gun an example of impossibility?
Yes. If a defendant intends to kill someone and fires a gun believing it is loaded, but the gun is actually unloaded, the case may involve factual impossibility.
Does impossibility mean there was no criminal intent?
No. In many cases, the defendant’s mistaken belief is evidence of the criminal intent necessary for an attempt.
Is factual impossibility a defense to attempted murder?
Generally, not automatically. If the defendant intended to kill and took legally sufficient steps toward the killing, the fact that circumstances made the killing impossible may not defeat attempt liability.
Does the Model Penal Code recognize factual impossibility as a general defense?
The Model Penal Code’s substantial-step approach generally does not make factual impossibility a broad defense. It focuses on purposeful conduct and substantial steps strongly corroborating the criminal purpose.
Does legal impossibility always defeat an attempt?
No universal answer exists. The treatment depends on the jurisdiction, statutory language, and precise nature of the alleged offense.
Conclusion
Impossibility exposes one of the deepest ideas in the law of criminal attempts: criminal responsibility does not always depend on whether the intended harm was objectively capable of occurring.
A person who tries to steal from an empty pocket may have demonstrated the same criminal purpose as someone who reaches into a pocket containing a wallet. A person who fires an unloaded weapon may demonstrate the same homicidal intent as someone whose weapon fires. In such cases, the law may focus on what the defendant intended and how far the defendant went toward carrying out that intention.
But impossibility has limits.
Criminal law cannot punish a person merely because the person imagined a nonexistent crime. The prosecution must establish an actual target offense, the required mental state, and legally sufficient conduct. The principle of legality remains essential.
The modern approach therefore tends to reject the idea that “it could never have worked” automatically means “there was no attempt.”
Instead, the central question becomes:
Did the defendant, with the required criminal purpose, take legally sufficient steps toward committing an actual offense, even though circumstances prevented completion?
Where the answer is yes, impossibility may not save the defendant from attempt liability.
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The information provided in this article ("Impossibility in Criminal Attempts") is for general educational and informational purposes only and does not constitute formal legal advice. Reading this content does not create an attorney-client relationship. Laws vary by jurisdiction; consult a licensed attorney for specific legal matters.
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