The police are authorized to stop you and question you for investigative purposes when they reasonably suspect that you have committed a crime, are about to commit a crime, or when they see you committing a crime. If they have stopped you, you are required to identify yourself by providing your name, address, and date of birth if they request that you do so. While you do not need to provide them with any more information than this, you should provide this information forthwith and honestly to ensure that you are not charged with obstructing a peace officer.
In order to protect the public from impaired drivers and to otherwise ensure the safety of our roads, police are also authorized to randomly stop you and question you when you are operating a motor vehicle. They may ask you for your driver’s licence, vehicle registration, and insurance, all three of which you are required to provide. They may also inquire into whether you have consumed alcohol, and ask questions needed to determine whether your vehicle is mechanically roadworthy. Since you have a right to silence, you do not have to answer their questions, but it is advisable to cooperate with the police. Refusing to cooperate with them, particularly when they ask you to provide a sample of your breath, can lead to you being charged with criminal offences like a refusal or obstruction of a peace officer.
While the police are not prohibited from approaching you and asking you questions if you are not under investigation, you are not legally obligated to answer them unless they are asking for your licence while engaged in an activity like driving or hunting. Even if you have been arrested, you are not legally obligated to answer police questions, other than providing your name, address, and date of birth. Since any and all statements that are made to the police can be used against you, you should not answer any questions beyond those required to identify yourself.