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Challenging the Validity of Blood Alcohol Content Tests
Those suspected of a DUI offense may challenge a finding that their blood alcohol content was over the legal limit

The validity of breath and blood alcohol tests have come increasingly into question since a recent Colorado Springs Crime Lab audit revealed that many of the blood alcohol content (BAC) levels reported by the lab were inflated. As the BAC levels reported by the lab are often used to help convict or acquit people charged with driving under the influence (DUI) offenses, the possibility that reported inflated levels may have lead to unfounded convictions has alarmed many in the legal community. As a result of the audit, 167 DUI convictions have been called into question.

The suspected human errors that lead to reports of inflated BAC levels in the Colorado Springs Crime Lab are not the only kinds of errors that can occur in BAC testing. In fact, there are many reasons to legitimately challenge BAC testing when defending against a DUI charge. If BAC testing is successfully challenged in court, it becomes very difficult to convict a person charged with a DUI offense.

Preliminary Tests

When an officer pulls over a suspected drunk driver, she may offer the suspect a portable breath test. This test is not admissible in court. As such, a suspect has the right to refuse the portable breath test without facing any punishment. The portable test is only used to aid the officer in establishing the probable cause she must have before arresting a suspect. If you are pulled over and an officer requests that you submit to a portable breath test, you may refuse. However, you may not refuse a breath or blood test at the police station or hospital without punishment.

If the officer asks a suspect to submit to a breath or blood test at the hospital or police station, the suspect will incur harsh penalties for refusing to submit to the testing. In addition to facing penalties such as a suspended license and fines, the prosecutor will be able to tell the jury that the suspect refused to submit to BAC testing and imply the suspect’s guilt. If the suspect submits to breath or blood testing and the tests result in a report of an elevated BAC level, an attorney may challenge the tests themselves, which can result in acquittal of the suspect.

Breath Tests

Breath tests attempt to determine the BAC of a person by measuring a deep-lung sample of breath. Deep-lung exhalations are said to accurately reflect the concentration of alcohol in the blood. However, many factors can cause a BAC breath test to deliver inaccurate results. Some of these factors include:

  • Variance in the volume or flow rate of exhaled breath which can cause an inaccurate result
  • Variance in air temperature, such as extreme heat or extreme cold
  • Improper calibration of the testing device or mechanical problems
  • Problems with interfering substances such as asthma spray or cough medicine, which may produce inaccurate results

In addition, breath tests can be challenged due to problems with procedure. For example:

  • Failure to observe the suspect for a certain period of time before the test is administered in order to ensure that the test is not tampered with
  • Failure to test more than one breath sample
  • Operator Error

Blood Tests

Blood tests of BAC are generally considered more accurate than breath tests and are thus harder to challenge on the basis of the BAC level itself. However, blood tests can be challenged on several other grounds:

  • An unlicensed person administered the blood draw
  • Calibration problems or other equipment issues
  • The blood was not drawn in the time period required by law
  • The blood was not properly preserved or stored
  • The “chain of custody,” which tracks who was in possession of the blood and responsible for making sure it wasn’t tampered with, is established and was unbroken
  • The blood was fermented, causing an improper elevation of BAC

For Further Reference

Given the severity of punishments imposed upon those who are convicted of operating a vehicle under the influence, it is important to fully understand the defenses suspected offenders may be able to assert. If you have been charged with driving under the influence of alcohol or drugs, please contact an experienced criminal defense attorney.

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