While police can lawfully ask you whatever they wish, you do not have to answer. Even if you have not done anything wrong, your answers could come back to haunt you. If police are investigating an offence and ask you questions, it may be best to politely decline to answer particularly if you are a suspect.
It is almost always best not to go or say anything. You have a right to remain silent. If you do make a statement to police, signed or oral, the Crown may be able to use it as evidence against you. If you’ve been arrested or detained police must tell you that you can immediately contact a lawyer. If you say you want to do so, police must hold off further questioning until you’ve spoken with one. A lawyer will likely tell you not to answer police questions. But once you’ve spoken to a lawyer, police may question you further – even if you tell them “my lawyer told me not to answer any questions.” Generally, it is best to meet with a lawyer before you co-operate with police. You should fully discuss the benefits and consequences of co-operation.
If you do speak to the police, don’t lie. Lying to police could lead to criminal charges of public mischief, obstruct police or obstruct justice; a false alibi could become evidence of consciousness of guilt. The risk of speaking to police is that even an honest, but mistaken statement, can be later used at your trial as a prior inconsistent statement to attack your credibility. If you have an alibi, do not tell police at the time of your arrest; your lawyer should investigate your alibi before it is disclosed.
Do not take part in such tests. The results are not admissible at trial. Police know this but use these tests to get you to confess. Unlike the test results, your statements may be used in evidence.
If in the course of investigation by police you suffer an injury, it is important to have it viewed by a doctor as soon as possible. Try and get photos.