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Basics of DUI Laws

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What are the Basics of Driving Under the Influence (DUI) Laws?

All states have their own laws regarding penalties for driving while impaired by drugs or alcohol. Impaired driving laws can go by a variety of names and definitions including: 

What Substances Make Me Susceptible to a Possible DUI Conviction?

It's important to keep in mind that alcohol is not the only substance that can result in a DUI conviction. Any substance, legal or illegal, that can inhibit your cognitive abilities and coordination can result in a DUI.

  • Alcohol;
  • Banned or Illegal drugs;
  • Marijuana;
  • Prescription medications such as painkillers; and
  • Overdoses of over-the-counter medications such as antihistamines.

What are the Dominant DUI Tests Out There? 

  • Field Sobriety Tests: Typically involve a police officer asking a driver to perform several tasks that assess a person's ability to control their physical movement (e.g. one-leg stand test, walk and turn test). Sometimes officers also test cognitive ability by asking people to answer simple questions (e.g. ABC tests).
  • Field-Administered Chemical Test: Sometimes an officer may conduct a chemical test in the field. Typically, this amounts to a Breathalyzer test that measures blood-alcohol content.
  • Hospital Administered Chemical Test: Some police departments, in addition to the field administered chemical tests will retest persons in custody in a proper health facility or hospital. These tests will typically be blood and urine tests.

What is the Implied Consent Law?

All states have some sort of “Implied Consent” laws regarding a police officer’s right to submit a driver to a chemical test when there is probable cause to believe the driver is operating the vehicle while impaired. 

Generally, implied consent laws state that by holding a driver license, it is implied that you have given your consent to submit to a chemical test (e.g. breath test) upon being arrested for a DUI. A driver may still refuse to submit to a chemical test but doing so will often be considered the same as failing the chemical test and in some states will carry a harsher penalty.

What are "Per Se" and "Zero Tolerance" DUI Laws?

"Per Se" DUI laws state that if an individual is shown to have a blood-alcohol concentration (BAC) at or above 0.08%, that person will be considered to be intoxicated under the law without needing any other evidence.

Whereas "Zero Tolerance" laws are applied to underage drinkers (generally under the age of 21) and consider them intoxicated under the law if they have even a trace of alcohol in their system.

What Effect Will a DUI Have on My Driving Rights?

In most places a charge for driving under the influence will lead to immediate suspension of your driver's license. Some states will confiscate or impound your car until the suspension has ended. The length of the suspension of your driving privileges will oftentimes depend on your history of DUI incidence and the severity of the particular DUI offense. 

For habitual offenders, some courts are now requiring ignition interlock devices to be installed on the offender's car. These devices utilize a miniature blood-alcohol device to keep the person from starting the car if above the legal limit.

Do I Need to an Attorney?

DUI charges can result in serious consequences such as fines, driver license suspension or revocation, impounding your vehicle, and even jail time. A local DUI lawyer will help you evaluate the facts of your case and determine any rights or defenses available to you. In addition, a skilled attorney can make motions on your behalf, depose the arresting office, gather evidence, and represent your interests in court.

Photo of page author John Kirby

, LegalMatch Legal Writer

Last Modified: 07-24-2018 12:28 AM PDT

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