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Difference Between Chemical Sobriety and Field Sobriety Tests?

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Posted By McAdams Law | May 31 2023 | Blog, DUI

You should know your rights if you have consumed alcohol before driving and encounter law enforcement during a traffic stop. Losing your driving privileges can severely impact your life, so knowing what to expect in an encounter with law enforcement is essential. Working with the team at McAdams Law Office will ensure you receive the respect and representation you deserve if you are facing a DUI offense in Colorado.

Know Your Rights

If you are stopped and suspected of DUI in Colorado, two tests are used to determine your level of intoxication. Understanding if you are required to submit to these tests is crucial.

Determining Sobriety

You may be asked to submit to two types of tests when you are suspected of a DUI to determine your sobriety. We explain those below.

Field Sobriety Tests

Field sobriety tests are usually administered on the roadside by an officer who suspects a driver of DUI and allows law enforcement to observe the driver’s behavior, only establishing probable cause for a DUI arrest. The officer will generally have the driver perform a series of tests considered standardized field testing. These three tests are deemed the most reliable.

  • Horizontal gaze nystagmus
  • Walk and turn
  • One-leg stand

There are additional field sobriety tests considered non-standardized that the driver may be asked to perform.

Possible Factors Affecting Field Sobriety Testing

A DUI attorney with insight into the dynamics of these tests can offer valuable arguments against the validity of these tests. What are some of the factors that may influence the performance in a field sobriety test?

  • Environmental factors such as weather or blinding traffic
  • Intimidation or anxiety
  • Medical conditions such as multiple sclerosis and other diseases that interfere with balance
  • Age
  • Medications
  • Physical disabilities and injury

Chemical Sobriety Test

Under Colorado law, drivers agree to what is known as expressed consent when operating an automobile. If a driver is suspected of impairment, the officer will request that a battery of chemical tests be administered. Chemical sobriety tests are the collection and analysis of the following:

  • Breath
  • Blood
  • Urine

These tests use standard scientific measurements but are not without fault.

Possible Factors Affecting a Chemical Sobriety Test

  • Improper machinery calibration
  • Lab errors
  • Sample contamination
  • Diet
  • Use of mouthwash, cough drops, and some asthma medications

Can You Refuse to be Tested in Colorado

You are under no legal obligation to perform field sobriety tests. Field sobriety tests are voluntary. If you do not want to submit to field sobriety tests, you should politely but firmly refuse to leave your car.

You cannot refuse chemical sobriety testing in Colorado because of expressed consent, mentioned above. If you refuse blood or urine collection, your license may automatically be revoked.

Reinstatement of your license will require an interlock ignition device after two years. Additionally, documentation of completion of an alcohol education program will be required. You may also be required to purchase SR22 insurance for a specific period.

Becoming familiar with the tests and Colorado law requirements is critical for drivers.

Experienced Colorado DUI Defense Attorney

Charges from an alcohol-related offense can be costly and impede your ability to function at home and work. Our focus on building solid cases can protect your best interests while being treated respectfully. Contact our team to understand your rights when field and chemical sobriety tests are implemented.


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