Like any other crime, impaired driving needs to be proven in a court of law. If you’re charged and the crown feels like it doesn’t have enough evidence to convict you, it may drop the charges. The charges can also be dismissed after the evidence is presented in court.
In Canada, a DUI (Impaired Driving) is a very serious criminal conviction, and so if you’re charged, you should get a lawyer and do everything you can to avoid a conviction.
If you’re convicted, that conviction will affect your insurance rates for 3 years, but may affect other areas of your life (career,
international travel, adoption, volunteering) for much longer. The only way to get the conviction removed from your record is to apply for a pardon. You are eligible to apply for a pardon 5 years after you pay your most recent fine, and more than 90% of applications are approved.