Opening the book…
Along with failure of proof defenses to the criminal act and criminal intent elements, legal impossibility and voluntary abandonment can also function as affirmative defenses to attempt in many jurisdictions.
Impossibility as a Defense to Attempt
Two types of impossibility defenses exist: legal impossibility, which can function as a defense to attempt, and factual impossibility, which generally cannot. Legal impossibility means that the defendant believes what he or she is attempting to do is illegal, when it is not. Factual impossibility means that the defendant could not complete the crime attempted because the facts are not as he or she believes them to be. The Model Penal Code disallows factual impossibility as a defense by stating that conduct is an attempt when the defendant “purposely engages in conduct which would constitute the crime if the attendant circumstances were as he believes them to be” (Model Penal Code § 5.01(1) (a)).
Example of Legal Impossibility
Review the example given in Section 8 “Res Ipsa Loquitur Test” with Melissa and Matthew and the attempted poisoning of the neighbor’s dog. Assume that Melissa is eighteen. Melissa believes that an individual must be twenty-one to purchase rat poison because that is the law in the state where she lived five years ago. Actually, the state in which Melissa currently resides allows the purchase of rat poison by those who are eighteen or older. The first store Melissa enters asks for identification when she tries to pay for the rat poison, so Melissa makes an excuse and leaves. The second store Melissa enters does not ask for identification, and she successfully makes the rat poison purchase. Melissa has probably not attempted to purchase rat poison illegally in the first store she entered. Melissa’s act in attempting to purchase the rat poison is legal under the circumstances. Thus her mistaken belief that she is attempting to commit a crime does not transform this legal act into an illegal one.
Example of Factual Impossibility
Recall from the example given in Section 8 “Res Ipsa Loquitur Test” that Matthew threw a filet coated with rat poison over the fence into the neighbor’s yard with the intent to poison the neighbor’s dog. Both Melissa and Matthew are under the mistaken belief that the dog is present and will eat the filet. However, the dog is on an overnight camping trip with its owners. This mistake of fact probably will not excuse Melissa and Matthew’s attempt. Melissa and Matthew purposely engaged in conduct that would result in the poisoning of the dog if the facts were as Melissa and Matthew believed them to be. Thus Melissa and Matthew have most likely committed attempted destruction of property or animal cruelty regardless of the fact that their plan could not succeed under the circumstances.
Voluntary Abandonment as a Defense to Attempt
Many jurisdictions allow a defendant who voluntarily abandons the planned offense to use this abandonment as an affirmative defense to attempt (Fla. Stat. Ann., 2010). The defense has two parts. First, the defendant must have a change of heart that is not motivated by an increased possibility of detection, or a change in circumstances that make the crime’s commission more difficult. As the Model Penal Code states, “it is an affirmative defense that he abandoned his effort to commit the crime…under circumstances manifesting a complete and voluntary renunciation of his criminal
purpose…[R]enunciation of criminal purpose is not voluntary if it is motivated…by circumstances…which increase the probability of detection…or which make more difficult the accomplishment of the criminal purpose” (Model Penal Code § 5.01(4)). Second, the abandonment must be complete and cannot simply be a postponement. Under the Model Penal Code, “[r]enunciation is not complete if it is motivated by a decision to postpone the criminal conduct until a more advantageous time or to transfer the criminal effort to another but similar…victim” (Model Penal Code § 5.01(4)). The voluntary abandonment defense gives defendants incentive to stop progressing toward consummation of the offense and prevents the crime from occurring without the need for law enforcement intervention.
Example of Voluntary Abandonment as a Defense to Attempt
Review the example with Melissa and Matthew in “Res Ipsa Loquitur Test”. If Melissa changes her mind after purchasing the rat poison and talks Matthew out of poisoning the neighbor’s dog, Melissa has voluntarily abandoned the crime and cannot be charged with attempt. If Matthew changes his mind after coating the filet with rat poison and throws the filet away, Matthew has voluntarily abandoned the crime and cannot be charged with attempt. Note that both Melissa’s and Matthew’s actions are in the very early stages of the crime of destruction of property or animal cruelty and probably will be considered preparatory, rather than constituting the criminal act element required for attempt. When Melissa climbs over the fence, picks up the filet, and takes it back to her house for disposal, it is most likely too late to voluntarily abandon the crime. At this point, the crime of attempt has already been committed, and neither voluntary abandonment nor factual impossibility can function as defenses.
This page titled 7.1.11: Defenses to Attempt was last modified on Tue, 01 Sep 2026 15:41:40 GMT and is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Mark C Fields and Carmyn A. Radetic-Fields.
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