DWI/DUI Practice Center

What is a DWI?

DWI stands for "driving while intoxicated." Intoxication can mean either alcohol or drugs . You will be charged with a DWI if your blood alcohol level is 0.08% or higher when your car is stopped by a police officer.

What is BAC?
BAC is an acronym for Blood Alcohol Content. BAC is the amount of alcohol in your blood. BAC is stated as a percentage, it is the analysis of the amount of alcohol in your blood.

How is Blood Alcohol Content Measured?
Blood alcohol level is calculated in four different ways:

  • Urine testing
  • Breath
  • Saliva
  • Blood

The test is usually administered immediately after you are pulled over on suspicion of DWI. Currently, breath tests are the most frequent method to collect evidence of a suspected DWI. The breathalyzer is the device used to administer a breath test.

Is There a Difference Between a Breathalyzer and BAC?
A breathalyzer does not determine blood alcohol level, but attempts to approximate the amount of alcohol in your breath from your lungs. Assuming a certain ratio of 2100:1 between the two, breathalyzers interpret breath alcohol content to blood alcohol. However, this ratio is a general calculation and varies between 1700:1 and 2400:1 depending on the person. Because the conversion isn't exactly precise for every driver, breathalyzer analysis results are often challenged in court.

Does the Law Require that You Submit to a Breath Test?
If the breath test is refused by a motorist, law enforcement must then determine if their "observations" are enough for probable cause to arrest you on DWI. In deciding to refuse the breath test, certain consequences can result.

Some of the consequences include:

  • In several states refusing the breath test can result in presumable "consciousness of guilt evidence"
  • An automatic suspension of your driver's license

What Are Field Sobriety Tests?
The National Highway Transportation Safety Administration, or NHTSA, offers a standardized model for field sobriety analysis. The NHTSA model calls to administrator three field sobriety examinations.

  1. The Horizontal Gaze Nystagmus (HTN) Test
  2. The WAT, or Walk and Turn Test
  3. The One Leg Stand Test

Field sobriety tests may be significant pieces of evidence in DWI cases when breath/blood tests have been found unreliable or when a breath test or blood test was refused. In some cases, these tests may not have much impact in DWI cases.

What is Zero Tolerance?
Zero tolerance makes it illegal for any person younger than 21 years of age to operate a vehicle with any alcohol in their system. The phrase "Any alcohol" can vary in definition from state to state, but is certainly different from being intoxicated. In other words, it is not necessary for them to prove impairment but is required to show the driver had the designated concentration of alcohol in their blood. In most states, for underage drivers .02% is the "designated concentration.”