A person's mental health in relation to criminal law proceedings is relevant in two ways. First, the person must be fit to plead to the charge. If it is shown that the person, because of insanity, is unable to understand the charge against him or the difference between guilty and not guilty, or is unable to instruct counsel, challenge jurors, or follow the evidence, the trial cannot proceed. This is essentially because its fairness cannot be guaranteed due to the person's condition. The test at common law to be followed in such instances was laid down by the Supreme Court in the State (Coughlan) v. Minister for Justice (1968). This test is not limited to any particular definition of insanity; it simply assesses the person's ability to comprehend what is going on. If the person is found to be unfit to plead, section 2 of the Criminal Lunatics Act 1800 provides that he or she should be detained in strict custody until the pleasure of the Government be known.