Driving under the influence

Driving under the influence (DUI) or Driving while intoxicated (DWI) is the crime of driving a motor vehicle while impaired by alcohol or other drugs (including those prescribed by physicians), to a level that renders the driver incapable of operating a motor vehicle safely. The name of the offense varies from jurisdiction to jurisdiction and from legal to colloquial terminology. Other terms include: drink-driving, drunk driving, drunken driving, impaired driving, operating under the influence, drinking and driving, over the prescribed limit (OPL). People who receive multiple DUIs are often struggling with alcoholism or alcohol dependence.

With alcohol, a drunk driver's level of intoxication is typically determined by a measurement of blood alcohol content or BAC. A BAC measurement in excess of a specific threshold level, such as 0.05% or 0.08%, defines the criminal offense with no need to prove impairment. In some jurisdictions, there is an aggravated category of the offense at a higher BAC level, such as 0.12%.

Impaired driving in Canada

Impaired driving is the term used in Canada to describe the criminal offence of operating or having care or control of a motor vehicle while the person's ability to operate the motor vehicle is impaired by alcohol or a drug. Impaired driving is punishable under multiple offences in the Criminal Code, with greater penalties depending on the harm caused by the impaired driving. it can also result in various types of driver's license suspensions.

There is a related, parallel offence of driving with a blood alcohol lever which exceeds eighty milligrams of alcohol in one hundred millilitres of blood (.08). The penalties are identical for impaired driving and driving with a BAC greater than .08.

The Criminal Code gives the police a number of powers to assist in the enforcement of the offences, and there are a number of presumptions that assist in the prosecution of the offences.

History

One of the first reported criminal cases regarding drinking and driving in Canada was an Alberta decision in 1920 called R. v. Nickle. In that case, the appeal court found that the act of driving while intoxicated was an unlawful act that could support a manslaughter conviction.