Legal Definitions - driving while intoxicated

Driving While Intoxicated (DWI) refers to the criminal offense of operating a motor vehicle after consuming enough alcohol to impair one's ability to drive safely. This impairment is typically measured by a blood alcohol content (BAC) level that exceeds the legal limit established by state law, which is commonly 0.08% for most drivers. It's important to understand that a driver does not need to appear "completely drunk" to be charged with DWI; merely having a BAC above the statutory threshold is sufficient. Additionally, a DWI charge can be based on other observable evidence of impairment, even if a precise BAC reading isn't immediately available or conclusive. Laws and specific BAC limits can vary by state, and some jurisdictions may use the term "Driving Under the Influence" (DUI) interchangeably or to denote a broader category that might include impairment by drugs as well as alcohol.

• Scenario: The Late-Night Stop

  After attending a company holiday party, Sarah decides to drive home. She feels "fine" but had several alcoholic drinks over a few hours. A police officer pulls her over for a broken taillight. During the stop, the officer notices Sarah's eyes are a bit glassy and detects a faint smell of alcohol. Sarah agrees to a breathalyzer test, which shows her BAC is 0.10%, exceeding the legal limit of 0.08% in her state.

  Explanation: This is a clear instance of DWI because Sarah was operating a motor vehicle with a blood alcohol content (BAC) above the legally permissible limit, even if she didn't perceive herself as heavily intoxicated. The objective measurement of her BAC is the primary evidence for the charge.

• Scenario: The Minor Accident

  Mark is driving home from a bar and, while attempting to park, scrapes another car. The owner of the other car calls the police. When officers arrive, they observe Mark struggling to maintain his balance, slurring his words, and having difficulty following simple instructions. Although a breathalyzer isn't immediately available, the officers administer field sobriety tests (like walking a straight line or standing on one leg), which Mark fails significantly. Based on these observable signs of impairment, Mark is arrested for DWI.

  Explanation: This example illustrates DWI based on observable evidence of impairment, even without an immediate BAC reading. Mark's slurred speech, poor balance, and failure of field sobriety tests provide sufficient "other evidence of intoxication" to support a DWI charge, demonstrating that impairment itself can be a basis for the offense.

• Scenario: The Commercial Driver

  David, a professional delivery truck driver, has a beer with his lunch. Later that afternoon, during a routine traffic stop for a vehicle inspection, the officer notices a slight odor of alcohol. David takes a breathalyzer test, which registers a BAC of 0.05%. While this might be below the legal limit for a standard driver, the legal limit for commercial drivers in his state is 0.04%.

  Explanation: David is charged with DWI because, as a commercial driver, he is subject to a stricter legal BAC limit. Even though his BAC might be below the general limit for non-commercial drivers, exceeding the specific lower threshold for his profession constitutes driving while intoxicated under the law.