A defendant who raises the necessity defense admits to committing what would normally be a criminal act, but claims the circumstances justified it. Normally, to establish a necessity defense a defendant must prove that:
- There was a specific threat of significant, imminent danger.
- There was an immediate necessity to act.
- There was no practical alternative to the act.
- The defendant didn’t cause or contribute to the threat.
- He or She acted out of necessity at all times, and the harm caused wasn’t greater than the harm prevented.
Traditionally, the necessity defense isn’t available to a defendant who kills an innocent person, regardless of the circumstances.
In almost all cases where a serious crime has taken place, necessity is unlikely to be a successful defence as courts have mostly taken the view that directly harming another person could not be justified even by extreme circumstances unless it directly prevented immediate serious harm or death.
Even if a person were already likely to die, and their death would allow others to survive, killing them is not necessary until the point where harm is imminently likely to occur to the others and if that harm is not immediate, then necessity cannot apply.
As such the circumstances where necessity could apply to a serious crime are extremely narrow, involving two or more people in an immediately life-threatening situation where only one could survive. Even in this situation, as the law does allow for a person not to take actions that would save another person if to do so would put their own life at risk, it is seldom strictly necessary for one person to kill another, one allowing the other to die in the course of the situation, then saving themselves.
The Prosecution will normally exercise its discretion not to prosecute those cases where it believes potential defendants have acted reasonably in all the circumstances, and as such where necessity is a strong defence.