There are two ways in which the mental condition of an accused person can become an issue in a criminal trial.
This page gives a brief overview of how the first question is dealt with. The matter of exemption from criminal responsibility on account of mental disorder is dealt with separately.
The rules about mental disorder are found in Part XX.1 (Part 20.1) of the Criminal Code. Please note that, as with all the other topics discussed at this site, we are only providing a glimpse into this particular area of the criminal law. If your interest in it is more than casual, make sure you get legal advice, or at least study the law in much greater detail yourself.You cannot just put a person to a criminal trial if you clearly see that his or her mental health is not good. There are a lot of different cases where people are not being issues in a criminal trial because of their mental health. Of course, this doesn’t mean that these people will walk away freely, just that they will be sent to a specialized place.
As we mention in our notes on trial principles, an accused person has the right to be present at trial, to confront his or her accuser, and to make full answer and defence. When an accused is incapable of understanding the proceedings, he or she cannot really be considered to be “present” for those purposes.
The Criminal Code [s. 2] says a person is unfitting to stand trial if he or she suffers from a mental disorder that prevents him or her from conducting a defence, or instructing counsel to do so. In particular, this means an inability to understand the nature or object of the proceedings, or their possible consequences, or to communicate with counsel.
The issue of fitness is then tried separately from the trial on the charge itself. If that main trial is to be by jury, then a jury also decides the question of fitness, and it can be the same jury. If the main trial is to be by judge alone, or if there is to be a preliminary inquiry, the question of fitness is decided by the judge.