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Defense Strategies to Know in a DUI Case

Police officer with breathalyzer

There are more than 1 million arrests in the United States for driving under the influence of drugs and alcohol annually, according to the FBI. Just because someone was arrested does not mean they are guilty. Every person arrested for driving under the influence (DUI) should be investigating the potential defense strategies that exist in each case.

The strategies and training that law enforcement utilizes are the same all over the country. The same is true regarding the science behind the measurement of the number of drugs or alcohol in a person’s body. Therefore, the following defense strategies are universal.

Importance of Having a Skilled DUI Defense Lawyer

The evidence in a typical DUI prosecution is very specialized. Law enforcement’s DUI investigation strategies have become standardized and taught to police all over the country. Despite this, the measurement of alcohol and drugs is extremely scientific.

Any lawyer seeking to provide a legitimate defense to a DUI prosecution must be educated and trained in each of these fields. The National Highway and Traffic Safety Association (NHTSA) has created an entire course for law enforcement on how to conduct DUI investigations.

The defense attorney must also take and become certified in this course. Further, a skilled DUI defender must know how a breath alcohol test device works, how blood is collected/analyzed and understand how to litigate these issues in court.

Additionally, a skilled DUI practitioner must learn and understand pharmacodynamics and pharmacokinetics. Pharmacodynamics is the effect of alcohol and drugs on the body. Pharmacokinetics is defined as the movement, absorption, and elimination of alcohol and drugs in the body. These are subjects that are not taught in law school.

A DUI defense will generally be considered a pre-trial or trial defense. It is also important that the defense lawyer is trained in DUI-specific trial techniques in order to assert the trial defenses.

Since the evidence is based on measurements, an expert DUI lawyer must be skilled in the science of metrology, which is the science of measurement.

Typical Evidence in a DUI Case

The most common evidence is the written police investigation report. It contains the arresting officer’s observations about the defendant’s driving, behavior, and performance of field sobriety tests. Unlike 20 or even 10 years ago, most DUI arrests are now captured by police from their dashcams and bodycam; the latter which includes audio from the officer’s body. This footage became essential in evaluating and defending a DUI case.

Most DUI cases result in an evidential breath alcohol test (EBT). Not only are these test results important, but so is the evaluation of all of the records that exist pertaining to the maintenance and testing of the breath test instrumentation. Additionally, there is often video recording(s) of the administration of the breath test, which can be very helpful in ensuring that proper protocol was followed.

In many cases, especially driving under the influence of drugs cases, a blood test is performed. The blood draw is typically performed by a medical professional, who will have written a report. This is important.

There will be paperwork that accompanies the blood specimen collection kit that should be evaluated. The blood analysis also creates a large volume of data, which must be reviewed in many cases.

Without proper evaluation of the many different types of evidence in a DUI case, there cannot be an effective defense strategy. All of these pieces of evidence must be evaluated in conjunction with the local and applicable DUI statutes and ordinances.

Legal Defenses

Law enforcement cannot do anything they want in a DUI arrest. By law, they must support the defendant’s constitutional rights at all stages of their investigation. Their failure to do so, despite eventually obtaining evidence suggesting guilt, can result in the suppression of evidence or case dismissal.

The Legality of the Traffic Stop

A police officer cannot stop any vehicle they wish. They must have witnessed a traffic infraction, or evidence amounting to a reasonable suspicion to believe the driver may be committing a crime, like a DUI.

Reasonable suspicion is an articulable belief based upon reasonable observations of evidence of a crime. For instance, if the police officer observed the driver continually weaving in and out of their lane, there is a reasonable suspicion that their ability to drive a motor vehicle is impaired. Therefore, an officer can legally justify this type of stop.

On the other hand, if a police officer witnesses the defendant exit a bar at 2 am following a Saturday night, those facts alone do not suggest enough reasonable suspicion to stop the vehicle. Doing so results in an unconstitutional seizure of the driver and can result in the dismissal of the prosecution.

Sufficiency of the Arrest

After the traffic stop, a police officer may not arrest an individual unless they have gathered enough evidence to suggest probable cause (a reasonable likelihood of guilt). All of the circumstances must be evaluated by the officer including:

  •     the observations of driving,
  •     observations of the driver,
  •     performance on field sobriety tests, and
  •     the results of a roadside breath or oral fluid test.

After a full evaluation of these and any other relevant facts, the officer still cannot make an arrest unless they have probable cause to believe the driver has committed a crime. If the officer does not have the requisite probable cause, the case can be dismissed. Further, any resulting chemical test that was obtained pursuant to the unlawful arrest can be suppressed.

The Legality of the Search Warrant

In some cases, such as when the arrested driver refuses to submit a breath test, a search warrant is obtained from a local magistrate to force the acquisition of the driver’s blood (since it is impossible to force a breath test).

The same requirement of probable cause is necessary before a lawful warrant is issued. If the officer’s affidavit does not contain the requisite probable cause in support of the search warrant request, the warrant can be squashed. Therefore, the evidence obtained will become suppressed. However, this does not happen in all cases.

The United States Supreme Court has created a “good faith exception” to the exclusionary rule that states if the officer relied in good faith upon the sufficiency of the warrant, even if there was not enough probable cause, the evidence will not be suppressed. Therefore, effectively challenging a warrant requires a heightened level of skill.

Breath Test Defenses

State law makes it a crime to operate a motor vehicle with a breath alcohol content (BAC) equal to or higher than .08 grams of alcohol per 210 liters of breath. Breath alcohol testing is the easiest and quickest manner of obtaining bodily alcohol evidence for a DUI case.

Because of this, most DUI arrests involve a breath alcohol test. The results of the breath test are often the strongest and most persuasive piece of evidence. Therefore, it is important to know how to defend against it.

Rising Alcohol Defense

Immediately after consumption, the amount of alcohol in a person’s blood or breath first rises during the period of absorption, reaches a peak, and then falls during a period of elimination. State law punishes driving while under the influence or having an unlawful BAC at the time of driving, not after.

Since an evidentiary breath test usually is conducted about an hour after driving, it is possible that a driver’s BAC was lower at the time of driving and potentially under the legal limit. This is typically a defense asserted at trial.

GERD and Diabetes

A person’s health or body can interfere with a reliable breath alcohol test. Gastroesophageal Reflux Disease (GERD) is a medical condition when the alcohol from a person’s stomach interferes with the breath test’s ability to accurately identify the amount of alcohol in the breath. Therefore, it is possible that the two sources of alcohol can be mixed to reflect a higher-than-accurate breath test result.

A person with type 1 diabetes may have acetone in their blood, which can transfer into their lungs. The breath test instrument cannot specify the acetone from the alcohol, thereby potentially reporting a false breath alcohol result.

Instrumentation Unreliability or Inaccuracy

No instrument or measurement is perfect. There are always limitations inherent in every breath alcohol test, which includes the measurement device and the people who administer it.

Every state has administrative rules about how the breath test machine should be maintained in order to ensure its accuracy and reliability. These rules typically include a schedule of instrument calibration, accuracy checks, and maintenance support. Further, the instrument operators (usually law enforcement officers) must also be trained and follow the rules on how to properly administer the test.

When the rules are not followed, the reliability and accuracy of the results are therefore compromised.

Blood Test Defenses

Administering blood tests for the identification and amount of drugs and/or alcohol is also very common in DUI cases. This is especially true for drug cases since a breath drug analysis machine isn’t available.

However, blood tests are more complicated and require further scientific knowledge. Due to the different stages of blood test evidence, there are more areas to consider for a potential defense.

Specimen Collection

If the blood specimen is not collected properly, the resulting blood analysis may be deemed unreliable or inadmissible. State DUI laws usually require the blood to be collected by a qualified and licensed individual. Furthermore, the collection technique may present microbiological contamination, which could make a test result inaccurate or unreliable.

Specimen Preservation

Blood is a biological substance that is subject to degradation if not handled properly and preserved. State law requires that specific blood collection vials are used, which contain chemicals designed to preserve the sample without refrigeration for a brief period of time.

This is intended to cover the amount of time necessary in delivering the sample to the lab. At this point, it is transferred to a temperature-controlled environment. A defense issue may be present when it takes longer than the expected period of time for the sample to be delivered to a lab and is not kept in a refrigerator.

Specimen Analysis

The actual determination of the identification and amount of alcohol and/or drugs can be an issue. The laboratory itself should be accredited by a third party. The forensic scientists must be properly trained and regularly evaluated. Finally, their laboratory methods should be in writing and subject to validation.

The actual analysis may present a defense issue. A blood sample that is being tested for alcohol must be properly prepared for analysis, as do the calibration and control samples. The instrumentation being used, such as a gas chromatography (GC) machine, must be in solid working order.

The analysis process involves the GC processing each unknown sample (which can be dozens in one run), as well as each calibrator and control. Therefore, the entire run produces a good amount of data that can be analyzed to determine if there were any problems.

These requests made to the laboratory can be voluminous:

  •     relevant run data
  •     reports
  •     operating procedures
  •     validation studies
  •     metrology reports
  •     sample reports (like chain of custody)
  •     validation study reports
  •     analyst background
  •     training and CV

Only scientifically trained and experienced attorneys (along with their team of experts) are able to properly evaluate this evidence.

Driving Defenses

Definition of “Operating” the Motor Vehicle

In order to determine criminal responsibility, there is often a question as to whether the person arrested was actually “operating” the motor vehicle. What if the driver was parked in a parking lot or on the side of the road? What if the evidence demonstrates that perhaps they were not driving?

Each state has case and statutory law that addresses these issues. There may be a defense strategy about whether the person arrested was actually driving. This defense may be asserted pre-trial or at trial, depending upon the circumstances and chosen strategy.

Evidence Admissibility

A defendant cannot be found guilty of a DUI charge if the necessary evidence is not properly admitted in court. Each state has standards or rules of admission. If these rules are not followed, a defense strategy may exist to keep the results from a jury’s consideration.

Breath Alcohol Tests

A typical requirement for an admissible breath test is for the breath test operator to be properly certified. That operator also must have followed the proper procedure outlined by the administrative rules.

Additionally, each state has rules about performance and documentation of the required accuracy and calibration checks. This documentation must be provided by an individual who has personal knowledge of their authenticity.

If any of these requirements are not satisfied, the results can be inadmissible. Breath test results are usually the strongest piece of evidence for the prosecution. This in itself could present a great defense.

Blood Alcohol Tests

There are a number of conditions that must be satisfied before a blood alcohol test can be admissible at trial. They may vary slightly depending on the state. Generally, it will be necessary for the prosecutor to introduce the blood draw technician to ensure compliance with rules, a proper chain of custody record and the actual forensic analyst along with their report.

In addition to admissibility, each of these witnesses can be cross-examined to illustrate a reasonable doubt in the results.

Standardized Field Sobriety Tests (SFSTs)

The law enforcement officer must demonstrate substantial compliance with NHTSA guidelines for the administration and evaluation of the SFSTs. Failure to do so can result in suppression of the evaluations.

In Conclusion

Every DUI case must be fully evaluated to identify the potential defense strategies in the case. After that, the strategy must be executed with skill and expertise. If the lawyer is not familiar with the applicable law, rules, training criteria, and forensic science, they cannot be effective in most DUI cases. However, an experienced DUI attorney can ensure that their client obtains the best results by employing effective strategies regarding the issues outlined above.

Barton MorrisAbout the Author
Barton Morris is one of the top DUI attorneys in Michigan. In addition to providing legal representation through The Law Offices of Barton Morris, he is currently the president of the Michigan Association of OWI Attorneys. Through this organization, he regularly teaches DUI defense strategies to criminal defense lawyers across the state. He has been on the faculty of both national DUI defense associations; the DUI Defense Lawyers Association (DUIDLA) and the National College for DUI Defense (NCDD).

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