The Motor Vehicle Act places obligations on drivers when they are stopped by police. You are always required, while driving, to stop and state your name and address to the police, as well as the name and address of the Registered Owner of the vehicle. It is an offence to fail to fulfill these requirements on demand. You should also be honest about your identity, because lying to the police about who you are will often result in a criminal charge for obstruction of a peace officer. That's a serious criminal offence, and can result in a criminal record.
You are also required to produce your driver's license, the vehicle registration, and your insurance documents to the police on request. Again, you can be ticketed for failing to do so which means that best practice is always to comply with these requests.
What you do not have to tell police when you're stopped
One of the most common questions drivers are asked when they are stopped is "Do you know why I pulled you over?" You do not have to answer this question. The police should not be asking you this question in any event, as they have an obligation under the Charter of Rights and Freedoms to promptly advise you of the reason why you have been detained. Even if the police persist, you do not have to answer this question. You have the right to silence, and the officer has an obligation to inform you of your detention. If you answer this question, you end up giving the police confirmation that you are aware of your guilt.
Sometimes the police will ask you "Where are you coming from?" or "Where are you headed?" These are trick questions. And again, you do not have to answer them. But if you start to say you're on your way to a party or a concert, the police will suspect you've been "pre-gaming." And if you say that you're on your way home from the bar or a restaurant, they'll assume you were drinking there. You just open yourself up to a world of grief if you answer these questions.
Another common question in traffic stops or at roadblocks is "Have you been drinking tonight?" The answer to this question may afford the officer grounds to investigate you for drinking and driving, demand breath samples, or demand that you perform sobriety tests. You are not required to answer, and there is no legal obligation on you to confirm with the police that you have been drinking or to tell them when you had your last drink.
This is where things get tricky though. If you do not tell the police you have been drinking, or you answer in the negative, the police may not learn about factors that can impact the reliability of their roadside breath testing equipment. If you've had a recent drink from a beer can hidden in your car, you might blow a false "Fail" and be issued an Immediate Roadside Prohibition. But if you answer there is no guarantee the police will conduct their investigation properly, and you could still end up in the same scenario.
Problems also arise when it comes to IRP review hearings. Even though the BC Supreme Court has confirmed that there is no obligation on drivers to provide information to police at any stage of an investigation (except the statutory requirement to provide your license, etc.), the RoadSafetyBC tribunal will often hold a driver's silence or untruthful response about drinking against them, saying "You lied at the roadside, so you're probably lying now" or something to that effect. Of course, if you say nothing you're less likely to face this type of reasoning.
So you're damned if you do admit to drinking, as you'll be asked to take a breathalyzer test. And you're damned if you don't and you end up blowing a fail.
So what are the consequences of staying silent?
Remember the recent scenario in which the Vancouver Police Department officer smashed a driver's window for refusing to exit the vehicle? Sometimes exercising your right to silence can get you in a lot of hot water. And in many respects, what you need to say and what you don't need to say is an evolving grey area of the law. Mostly for those damned-if-you-do-damned-if-you-don't reasons I've identified. Which makes it almost impossible for me as a lawyer to tell anyone how to answer the tricky little question "Have you had anything to drink tonight?" Maybe the best answer is "My lawyer says there's no way to answer that question or exercise my right to silence that will surely benefit me." But don't say that. You'll look guilty.
Then isn't it better to talk?
No. Absolutely not. It's not better to just volunteer information, even if you feel fine. There are many classic cases where people arrested for impaired driving say things along the lines of "I thought I was alright to drive" or "I guess I misjudged" that end up being the nail in their coffin. Remember, the police are also looking at you for symptoms of impairment. The more you speak, the more opportunities they have to listen for slurred speech, illogical statements, and slow responses to questioning.
Once you've been arrested and you're in the police custody you should not say anything else, except to assert your right to counsel. There is no point in talking your way out of a drunk driving arrest. It doesn't work, and it only reflects badly on you in the police report. Statements you make before you're arrested are only admissible for a limited purpose, but that doesn't mean they are not damaging to you.
As Canadians we are generally a polite society. A lot of people I talk to feel they are being rude if they don't engage in conversation with the police. While your best strategy is usually not to be a jerk, being polite can take the form of silence. You do not have to talk to the police. You are not obligated to talk to the police. They know that. They aren't going to be offended. Trust me, they're usually just happy you're not screaming obscenities or spouting off conspiracy theories. It's a nice break for them from that.
At the end of the day, silence is a good policy. Asking to call a lawyer is another one. Telling the police that you totally shouldn't have been driving and that you drank a six pack is a bad idea.