Legal impossibility occurs where the defendant does everything planed when going to commit a crime only to find that what they have done is not in fact a crime. It will not be an impossibility simply because the crime was not committed due to insufficient means or other reasons that make it improbable but not impossible.
If the attempt to commit an offence was possible but for the means available then it will not be classed as impossible. The test is one of objectivity. South Australian law has taken a slightly different approach to this defence, especially since the case of R v Irwin.
In the state of South Australia the only relevant facts are the intention to commit the offence along with actions manifesting that intention. Things such as insufficient means, legal impossibility and factual and possibility are not relevant.