When jailed by a police officer for suspicion of drunk driving, a driver’s most horrible nightmare begins. A cycle of steps will be undertaken by the police officer to determine if the driver is impaired by alcohol or drugs.

• The person may be given a breath test, often cited to as a breathalyzer because of the small instrument used to conclude the driver’s blood-alcohol content (BAC). This is the most widespread test. In some states the officer may choose whether a breath test, blood test, or urine test will be administered. While a breath test may be administered roadside or in a imprisonment center, blood and urine tests may only be administered in a imprisonment facility, hospital, or clinic setting. These choices are determined by that state’s DUI laws. Refusal carries a possible DWI penalty such as suspension of driving privileges.
  
• If a law enforcement officer suspects intoxication, field sobriety tests may be performed. The driver must perform simple physical or cognitive tests to establish sobriety. The most common requests are to walk a straight line heel-to-toe and spin at the end to return, or stand with feet together and tip the head backwards, or stand on one leg. The police officer may move a penlight in front of the person’s eyes and ask that the driver follow the light with the eyes. This is the “horizontal gaze nystagmus test,” which is quite new to field sobriety tests, and is reasonably accurate if administered right. The officer is gauging the angle at which the eye twitches; if this takes place at less than 45 degrees, it is a symbol of high blood-alcohol concentration.
  
• A Breathalyzer unit can be used, which is a small hand-held tool that measures the driver’s BAC (blood-alcohol concentration). This may be done roadside, at the detainment center, or at a hospital. Blood or urine tests can also be performed at a hospital.