What does mental impairment/fitness to be tried mean?

A person is not responsible for committing an offence if they were suffering from a mental impairment at the time of that crime.

  • Mental impairment means the person didn’t know the nature or quality of what they did, or that they didn’t know that what they did was wrong, or that the person was unable to control their behaviour.

If the jury decides the person was suffering from this sort of mental impairment at the time of the crime, then the jury must give a verdict of ‘not guilty because of mental impairment’.

  • Fitness to be tried is about a person’s physical and mental condition at the time they come to court, not at the time of the offence.

The question of whether a person is unfit to be tried can be raised by the defendant, their lawyer, the CDPP or the court.

Once it has been raised, the court must make a decision as to whether or not the person is fit to be tried.