Prosecution Approach

The National Highway Traffic Safety Administration (NHTSA) is an agency of the federal Department of Transportation dedicated to reducing the rate of vehicle-related crashes in the United States. As part of their work towards this goal, NHTSA has published “The Visual Detection of DWI Motorists”, an instructional guidebook used by law enforcement agencies to train staff in the investigation of impaired drivers. The guide includes 24 specific driving cues which may indicate that a driver is impaired. These cues are divided into 4 main categories:

Problems Maintaining Proper Lane Position

  • Weaving
  • Weaving across lane lines
  • Straddling a lane line
  • Swerving
  • Turning with a wide radius
  • Drifting
  • Almost striking a vehicle or object

Speeding and Braking Problems

  • Stopping too far, too short, or too jerkily
  • Accelerating or decelerating for no apparent reason
  • Varying speed
  • Slow speed

Vigilance Problems

  • Driving in opposing lanes/wrong way on a one-way street
  • Slow response to traffic signals
  • Slow or failure to respond to an officer’s signals
  • Stopping in lane for no apparent reason
  • Driving without headlights at night
  • Failure to signal or signaling inconsistently with driving actions

Judgment Problems

  • Following too closely
  • Improper or unsafe lane change
  • Illegal or improper turning
  • Driving on a surface other than designated roadway
  • Stopping inappropriately in response to an officer
  • Inappropriate or unusual behavior
  • Appearing to be impaired

While these guidelines have been developed based upon significant research conducted by the NHTSA, many of these “cues” are common driving behaviors that sober drivers commit every day. It is important to remember that if you have been charged with driving under the influence, the police officer who pulled you over must have had probable cause to believe that criminal activity was occurring. If your attorney can successfully challenge the existence of probable cause, your charges might be reduced or dismissed.

Physical Signs & Symptoms

Law enforcement officials are trained to look for specific behaviors that could indicate that a driver is intoxicated. During a DUI investigation, an officer will look closely for the following physical signs:

  • Difficulty with motor vehicle controls: During a DUI stop, the officer may ask you to perform a variety of tasks that will include the use of the controls in your car (such as rolling your window down, turning the vehicle off, etc). The officer will observe your performance of these tasks to evaluate whether you are fumbling or having issues completing the tasks.
  • Difficulty exiting the vehicle: If the officer asks you to leave your vehicle, he or she will watch you closely when you do, to see if you stumble or otherwise experience difficulty.
  • Fumbling with driver’s license or registration: Just as with the vehicle controls, you will be observed accessing the location of your license and retrieving your registration information.
  • Slurred speech
  • Repeating questions or comments / asking officer to repeat questions: Repeating anything you say or asking the officer to repeat something he or she has said will be attributed to intoxication.
  • Swaying, unsteady, or experiencing balance problems
  • Leaning on the vehicle or other objects: Issues with balance are viewed as a classic sign of intoxication; additionally, attempting to ameliorate or mask a balance problem by leaning on an object will be viewed as an indication that a driver has been drinking.
  • Slow response time
  • Providing incorrect information or changing answers: Officers will expect relatively quick answers to any and all questions. Hesitating before answering or changing your initial response will be viewed as evidence of intoxication.
  • Odor of alcoholic beverages

Field Sobriety Test Performance

A field sobriety test refers to a series of behaviors that law enforcement officials will ask that a driver undergoing a DUI investigation perform so that the officer may observe and check for signs of impairment. There are three major tests that officers conduct during vehicle stops:

1. The Horizontal Gaze Nystagmus Test: This will involve an officer asking a driver to follow an object with his or her eyes. The officer will move this object, asking the driver to look left and right. This test is designed to detect nystagmus, which is an involuntary jerking of the eyes as a person’s gaze travels to the side. Nystagmus is an indicator of intoxication.

2. The Walk and Turn Test: This will involve an officer give a suspect the task of walking a short distance, turning around and returning. The officer will give a series of directions (including how many steps to take, the length of each step and the process for turning around). This test is designed to evaluate performance when “attention is divided”; that is an individual must exhibit balance and dexterity (stumbling or any other off-balance sign is an indicator of intoxication) as well as mental clarity (the ability to remember and follow the officer’s directions).

3. The One Leg Stand Test: During this test, an officer will instruct a suspect to raise a foot for a set period of time, look at the raised foot, then return the foot to the ground. Just like with the walk and turn test, the ultimate goal of this test is to evaluate performance when an individual’s attention is divided.

Chemical Test Results or Refusal

The state of California has what is known as an “implied consent” doctrine for all drivers. This means that if an individual exercises driving privileges, he or she is required to submit to a test of the breath or blood if lawfully arrested for driving under the influence. Both tests are designed to measure your Blood Alcohol Content (BAC). The results of these tests can be used against you if you are charged with driving under the influence. You do have the right to select the type of test you wish to take. However, if the test you wish to take is currently unavailable, you will have to take the alternative.

Refusal to submit to a chemical test carries penalties that drivers could face in addition to the penalties for a DUI (it is possible for a driver to refuse a test and still be found guilty of DUI, incurring enhanced penalties). Such penalties can include a one-year suspension of driving privileges, additional days in jail, and a longer period of required attendance at DUI school.

During a DUI stop, law enforcement officials are required to notify drivers of the consequences of their refusal. If you were arrested and not informed of the potential consequences of refusing to take a chemical test, you will not face additional penalties for refusing to submit to one. If the police suspect you of driving under the influence of alcohol, you should be given the choice of taking either a blood or a breath test. However, if police suspect you of driving under the influence of drugs, you are required to submit to a blood test.

It is important to note that drivers are required to submit to a chemical test if he or she is lawfully arrested for driving under the influence. This means that if your criminal defense attorney is successful at challenging the grounds on which law enforcement pulled you over or placed you under arrest, you are not required to submit to chemical testing (and therefore would not face any additional penalties if you refused to do so).