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Challenges to Breath Tests

Prosecutors in Missouri use chemical tests as evidence that a driver was intoxicated when driving. Most driving while intoxicated (DWI) cases rely, in part, on these chemical breath, blood, or urine tests for a conviction. However, just because a chemical test appears to show you were over the limit does not mean the test is accurate. There are a number of ways to challenge chemical breath tests in a Missouri DWI to fight a criminal conviction and keep your record clear.  

A criminal conviction for a DWI will leave drivers with a criminal record, take away their driving privileges, and cost thousands in fines, fees, and higher insurance rates. Before pleading guilty to a DWI, make sure you understand your rights and defenses. Contact the Joshua Wilson Law Firm for help with your Missouri DWI arrest. 

Chemical Breath Testing in Missouri

There are three types of chemical tests used in Missouri: breath, blood, and urine. Breath tests only test for the presence of alcohol and are used when the driver is suspected only of being under the influence of alcohol. If the driver is suspected of being intoxicated by drugs and/or alcohol, a blood test may be used. Urine tests can also test for alcohol and/or drugs. 

Under Missouri's “implied consent” law, drivers are considered to have given their consent to chemical testing after a DWI arrest as a condition of driving in Missouri. You may not have remembered specifically agreeing to chemical testing but refusal to submit to a chemical test can mean your license will be revoked for 1 year

Types of Breath Testing: Roadside vs. After Arrest  

Chemical breath testing and implied consent can be confusing because there are separate types of breath testing that may be involved in a Missouri DWI case

  • Portable Breath Test (PBT)
  • Breath Test After Arrest

Portable Breath Test

The PBT, sometimes called a preliminary breath test or breathalyzer, is a handheld breath testing machine. This is the type of device used during a roadside stop. This device is used to give police probable cause to make an arrest but it is not used as evidence in court that the driver was over the legal limit. 

One reason these tests are not used as evidence in court is that they are not as accurate as the larger and more complex breath testing devices used in police stations or by highway patrol. They are also not part of the tests required by Missouri's implied consent law. If you refuse one of these portable breath tests, there are no direct penalties. However, drivers under the age of 21 are required to give a preliminary test if the officer has reasonable grounds to believe the driver is intoxicated. 

The police officer may imply that you have nothing to lose by doing one of these roadside tests, or that things will go better for you if you do, but you have the right to refuse a roadside breath test. Talk to your Missouri DWI lawyer if you have questions about how a breathalyzer could affect your case. 

Breath Test After Arrest

Missouri's implied consent law applies to chemical testing after an arrest. Under Section 577.020, RSMo., a driver has given consent to a breath, blood, saliva, or urine test if the driver is arrested for operating a vehicle while in an intoxicated condition. Most DWI cases where the driver is suspected of being impaired by alcohol only will be done with the breath testing machine. 

Chemical Test Refusal After Arrest

Under Section 302.574, RSMo., if a driver refuses to submit to a chemical test after an arrest, the officer will take away the driver's license and issue a temporary permit which is valid for 15 days. If you want to challenge the revocation, you have to formally request an administrative review within 15 days of the arrest. If you request a hearing, your suspension or revocation will be stayed until the hearing. 

Challenging Breath Test Results in Missouri  

If the breath test results show you had a blood alcohol content (BAC) of 0.08% or higher, this may be used as evidence to show the driver was driving with excessive blood alcohol content. (Commercial drivers can be charged with a BAC of 0.04% or higher). There may also be additional penalties or restrictions if the driver had a BAC of over 0.15% or 0.20% or higher. 

Just because the testing equipment showed you were over the limit does not mean that you were intoxicated or the tests were accurate. There are a number of ways the test could be inaccurate or malfunction making it appear like you were guilty. An experienced Missouri DWI defense attorney understands the science and laws behind these chemical tests to challenge them in court.  

Problems with breath testing devices, the test sample, and individual operating the machine could result in inaccurate results. Things that can skew the results of a breath test can include: 

  • Uncalibrated breath testing device,
  • Breath testing device not in proper working order,
  • Testing by an untrained individual,
  • Not following breath testing protocol, 
  • Not properly observing the test subject before and during the breath test, 
  • Improper instructions for the test subject, 
  • Medical conditions, or
  • Food, drink, gum, mints, or medication that give inaccurate results. 

Motion to Suppress Breath Test Evidence 

One of the ways to challenge breath test evidence in a Missouri DWI case is to file a motion to suppress breath or blood test results. This is generally done before the trial so that the inaccurate evidence cannot be used in court. There are a number of grounds to challenge the breath test evidence, depending on how the test was conducted and whether the machine was properly maintained and calibrated. 

Consult an Experienced Raymore DWI Attorney

Just because the police and prosecutors claim you are guilty of a DWI does not mean that you have to be convicted of a crime. Breath testing devices are not 100% accurate all the time. When the police make a mistake, you should not have to pay the price with a criminal conviction. Joshua Wilson is an experienced Missouri DWI attorney who has successfully helped clients avoid a DWI conviction. Contact the Joshua Wilson Law Firm today online or by calling (816) 331-9968.

Don't Hesitate To Contact Us Today

Time is of the essence in the majority of legal matters. If you are in need of legal representation for your family or criminal matters, contact The Joshua Wilson Law Firm at (816)331-9968 to begin your case evaluation today.

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