I know that if are MI you do not have the right to have the police believe anything you say. They automatically assume that you no longer have any sound judgement.
How do the police know? Because they did a records check and it is in my records stemming back from an incident in 1988 when I had to undergo mental testing to work in sensitive areas during the Calgary Olympics. Because of that I was also entered into the FBI database since they did background checks for the Olympics.