The defence of Impossibility
The defence of impossibility is a complete defence. An accused person can reply upon the defence of impossibility when it can be established that it was impossible for the accused to have committed the offence. Impossibility may come about because it is physically impossible that the accused committed a crime or because it is factual impossibility for an accused to have committed a crime.
An accused could raise impossibility as a defence circumstance where:
- The accused could not have committed the offence due to his or her physical abilities or attributes. For example, if the accused has a medical condition or physical disability that renders them unable to commit the alleged act.
- The accused was not committing an illegal act. For example, believing to be in possession of a drug of dependence that on testing is revealed not to be a drug at all.
- The accused was unaware of a legal duty to act. For example, failing to stop and render assistance after a motor vehicle accident because s/he was not aware an accident had occurred. The point should be made here that although it is impossible to stop at an accident you did not know occurred, it would be novel to suggest impossibility, it would be more appropriate to utilise the defence of honest and reasonable mistake of fact in this circumstance.
- The accused could not have committed the offence/s because he or she was not present at the time the offence has occurred. For example, the accused is charged with committing a burglary on a particular date, but they can produce travel documents proving that they were not in the city/state at that time.
In relation to this last point if an accused person seeks to use an alibi at trial, to show that an offence was impossible, they must notify the prosecution in writing well in advance and outline the circumstances of the alibi, so that the prosecution can make enquiries.
Impossibility and attempt
In Victoria, the law contains attempt provisions that consider impossibility irrelevant to criminal attempt in some circumstances. Section 321N(3) of the Crimes Act 1958 (Vic) states that a person may be guilty of attempting to commit an offence despite the existence of facts, of which he or she is unaware, that make the commission of the offence attempted impossible. The words ‘may’ in subsection 3 leaves space for the defence of impossibility to apply where what the attempter ‘did’, amounted to a less serious ‘attempt’ crime.
Impossibility can also provide a mitigating factor; the courts are sometimes willing to take into account both the seriousness of the attempted offence and the likelihood of its achievement when adjudicating matters: see Regina v Peckover  and Regina v Taouk (1992).
Depending on the circumstances of an alleged offence, it may be possible to defend the charge based on impossibility. As is always the case, the above document cannot be considered legal advice. If you have been charged with a criminal offence, you should call our office to speak to one our specialist criminal lawyers today, to see if this, or any other defence applies to your case.