Ten Defense Strategies for Fighting DWI Charges in Missouri

Given that a conviction for driving while intoxicated (DWI) can result in severe criminal penalties in Missouri, it is important for anyone accused of such crime to explore every legal defense available. Indeed, the failure to consider all relevant DWI defense strategies may lead to a criminal conviction that could have otherwise been avoided.

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While there are certainly several legal arguments that can be raised when challenging Missouri drunk driving charges , some arguments are more popular than others. With that being said, below is an outline containing 10 of the more commonly used DWI defenses in the Show-Me State.

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1. An illegal traffic stop

One of the most common ways to defend against allegations of drunk driving is to contest the legality of the initial traffic stop. In fact, a Missouri police officer typically cannot stop a motor vehicle unless he or she has probable cause or reasonable suspicion that the driver of the vehicle has committed a traffic violation or engaged in criminal activity.

For instance, a police officer usually cannot pull over a driver simply because the officer observes the person leaving a bar ― evidence of criminal behavior or a traffic infraction must first exist.

Ultimately, if a driver can prove that he or she was subject to an illegal traffic stop, any evidence of criminal activity obtained as a result of that stop ― including evidence related to drunk driving ― may be suppressed. And, if the evidence is suppressed, a DWI conviction is less likely.

2. Challenge the officer’s observations

Often times, much of the evidence used when seeking a DWI conviction is based on the observations of the arresting officer. This can include claims by the officer that the driver had poor balance or bloodshot eyes.

However, it is possible for a driver to exhibit these particular characteristics even if he or she is not intoxicated. For example, a pre-existing disability or injury can easily result in uncoordinated movement. Moreover, bloodshot eyes can often be attributed to lack of sleep, allergies or irritation caused by contact lenses. The most important thing to remember is that many reasons may exist to explain the observations of a police officer that are completely unrelated to alcohol consumption.

3. Challenge results of field sobriety tests

Normally, police will attempt to administer field sobriety tests when they suspect a driver has violated the state’s DWI law. Three common field sobriety tests employed by Missouri law enforcement include the walk-and-turn test, the one-leg stand test and the horizontal gaze nystagmus test, which is when police ask a driver to hold his or her head still and follow an object, such as a pen or finger, with his or her eyes alone.

However, one of the greatest issues with field sobriety tests is that the ability to pass such tests is dependent on the officer’s interpretation of the driver’s performance, which is largely subjective. And, just as a pre-existing injury or disability can impact whether or not a driver initially appears intoxicated, it can also affect his or her ability to complete many of these tests. Also, medications or other medical conditions can influence a driver’s performance when taking these tests.

In the end, if a driver can prove that his or her performance was impacted by factors unrelated to alcohol, he or she may be able to have the results of the field sobriety tests ruled inadmissible.

Free consultation: Questions about fighting DWI charges in Missouri? Contact a St. Louis DWI attorney.

4. Breathalyzer not maintained properly

Under Missouri regulations, all breathalyzers used to measure blood alcohol content (BAC) levels in DWI cases need to be properly maintained. In fact, these regulations require maintenance checks on breathalyzers at least once every 35 days. If these checks are not performed on a particular breathalyzer, any incriminating BAC results obtained using this machine may be deemed inadmissible ― not to mention unreliable.

Moreover, these maintenance checks must also be performed when the breathalyzer is initially put into service and every time the machine is repaired or recalibrated.

5. Breathalyzer test improperly administered

Breathalyzer results may also be suppressed if police or test administrators fail to follow proper procedure when conducting the tests. For example, in order for breathalyzer results to be admissible evidence, Missouri courts normally require proof that the test was performed:

  1. by following the state-approved techniques and methods;
  2. by a person holding a valid permit; and
  3. using approved equipment.

Therefore, test results may be inadmissible not only if proper procedure is ignored but also if an individual who does not have a valid permit administers the test.

6. Challenge breathalyzer results

A driver charged with DWI in Missouri can also dispute the actual results of a breathalyzer test. In fact, just because a breath analysis indicates that a driver has an illegal BAC level it does not guarantee he or she was intoxicated at the time of the initial traffic stop.

Indeed, given that it can often take time for a person’s system to absorb alcohol, breath test results may be questionable if an individual has a few drinks immediately before driving but is not actually tested until several hours later. In fact, under such circumstances, it is quite possible that the driver was below the legal BAC limit when initially stopped.

In addition, a driver may be able to challenge the effectiveness and/or reliability of a particular model of breathalyzer, although expert testimony is often needed to establish such a claim.

7. High BAC level due to “mouth alcohol”

A driver’s BAC level can also be artificially inflated due to “mouth alcohol,” which, as its name indicates, includes any traces of alcohol found in the driver’s mouth. Essentially, mouth alcohol can distort breathalyzer results since the machine may detect the presence of alcohol in the driver’s mouth, as opposed to just analyzing the air from his or her lungs.

Several factors can contribute to mouth alcohol, including the use of mouth spray, mouthwash or even cold medicine. Moreover, burping or vomiting can bring alcohol from an individual’s stomach to his or her mouth, also resulting in mouth alcohol.

8. Failure to properly conduct 15-minute observational period

Given that mouth alcohol can easily impact the results of a breath test, Missouri law requires a breathalyzer operator to conduct a 15-minute observational period prior to obtaining a breath sample. During this period, the operator must also remain close enough to the driver to “reasonably ensure” that he or she does not vomit, smoke or have any oral intake.

The basic idea behind the observational period is to ensure that any alcohol in the driver’s mouth has time to dissipate before a breath sample is taken ― thus reducing the chance of mouth alcohol affecting the test results. However, if the breathalyzer operator does not wait the required 15 minutes, or if he or she does adequately observe the driver to prevent vomiting and/or oral intake, any results ultimately obtained will be questionable at best.

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9. Challenge blood test results

Similar to breath tests, blood tests in Missouri must also be administered in accordance with very specific procedures. For instance, only appropriate medical personnel ― such as licensed physicians, registered nurses or trained medical technicians ― can withdraw blood for the purpose of determining BAC levels within drivers. However, this is merely one of several procedural safeguards that must be observed when administering BAC blood tests. And, like breath tests, if these safeguards are not all followed, the test results may be suppressed.

10. Failure to give all required warnings

Lastly, an individual may have defenses available if police fail to give him or her all required notices and/or warnings ― including the implied consent warning as well as notifying an individual of his or her Miranda rights. While these defenses are typically less common than many others, they can be very effective in the right circumstances.

As initially mentioned, many defense strategies exist in the context of Missouri DWI law, including many not discussed herein. Indeed, given the complexity of these laws in Missouri, it is virtually impossible to cover all possible defenses in a single article. Accordingly, if you are facing DWI charges in Missouri and are interested in learning what your potential defenses may be, you need to consult with an experienced DWI defense attorney today.