Scientific & Legal Defenses to a DUI Charge

The legal limit in Michigan is .08, but there are several scientific and legal defenses to a drunk driving charge. Government ad campaigns and slogans such as, "Over the Limit, Under Arrest," coupled with a misguided faith in the legal system result in many wrongful convictions. Unwittingly, innocent people accept plea agreements every day based upon faulty chemical tests. In other instances, guilty people plead guilty when legal defenses could have been successfully raised. The vast majority of DUI cases go unchallenged.

Machines, as well as police officers, make mistakes. A person accused of operating while intoxicated should never be overwhelmed by misgivings and doubt just because the government's machine claims that the driver was above the legal limit. Likewise, a guilty person should never assume that the police officer's case is rock solid. Police officers who make mistakes typically acknowledge those mistakes, and simple human error can result in a dismissal.

Legal Defenses: Winning Irrespective of Guilt or Innocence

The following are just a few general areas that tend to frequently provide defenses in drunk driving cases. The important thing to consider with these defenses is that these defenses do not depend upon whether the motorist was actually intoxicated. Whether the driver was intoxicated or sober, the prosecutor must be ready to respond to legal defenses.

The Traffic Stop

Although courts tend to give the greatest deference to police and prosecutors in drunk driving cases, there are a number of legal defenses that may require dismissal or suppression of critical evidence in DUI cases. Constitutional protections guard against unlawful traffic stops, mandating that a police officer must have a reasonable and articulable suspicion to stop a motor vehicle. Even when an officer might be able to articulate a reason for the traffic stop, the officer's justification for the traffic stop must also be reasonable. (This is a point of contention in many instances where patrol car videos impeach an officer's testimony regarding the reason for the traffic stop.)

When an officer makes an unlawful traffic stop, all evidence following that unlawful stop is suppressed as "fruit of the poisonous tree," a doctrine developed to deter police misconduct. Some departments actively engage in patrolling bar parking lots, encouraging officers to justify the traffic stop after the fact. When these stops are clearly unconstitutional intrusions, they should be harshly condemned, but the financial rewards coupled with the fact that the driver "actually" turned out to be drunk provide an incentive to ignore these infringements.

The Arrest Decision

Another area where courts tend to give great deference to the officer is the arrest decision. A police officer making a warrantless arrest must have probable cause to believe that a crime has occurred. Probable cause is a higher standard of proof above the lower standard of reasonable and articulable suspicion. The Fourth Amendment to the United States Constitution prohibits unreasonable searches and seizures. The language of the amendment applies equally to seizures of a person, i.e. an arrest, as well as seizures of property. Searches and seizures conducted without a warrant are unreasonable per se, unless a clearly delineated exception to the warrant requirement is established by the prosecution. In other words, the prosecutor bears the burden of proving that probable cause exists to justify the warrantless drunk driving arrest. Interestingly, the arresting officer's good faith belief that a person may be intoxicated is not sufficient to establish the validity of a warrantless arrest under prevailing constitutional law, but the courts often times defer to stock, routine language regarding the "totality of circumstances."

Operation: The Sleeping Motorist

In order for a motorist to be found guilty of a drunk driving crime, the prosecutor must prove that the driver was intoxicated at the time of operation. A sleeping motorist is not "operating" under Michigan's drunk driving laws. (It is important to understand that not all states agree with this approach. In Ohio, for example, it is illegal to sleep in a vehicle while intoxicated.) When it is merited, a prosecutor can provide circumstantial evidence to a jury that a person drove drunk and then passed out, but a person who removes a vehicle from a risk of harm of causing a collision is not operating a motor vehicle under Michigan law. Whether the car is running and the location of the car keys does not matter, but this popular myth persists.

The Proper Foundation for Admission of Evidence

It is well-established that the proponent of evidence bears the burden of establishing the relevance and admissibility of evidence in any trial, including drunk driving cases. Since the prosecutor maintains the burden in DUI cases, many foundational arguments can succeed in a drunk driving case. The chemical tests can be suppressed if the prosecutor is unable to establish the proper foundation for that test's admission. If a police officer improperly administers a breath test, for instance, the test might be suppressed even if it tends to reveal that the driver was intoxicated. Foundational arguments can also include attacks against the sufficiency of field sobriety tests. For instance, a prosecutor must prove that a police officer was properly trained and properly performed the HGN field sobriety test before it can be admitted into evidence.

Access to Exculpatory Evidence

The prosecutor is under an affirmative obligation to provide the defense with exculpatory information relating to the case. Many prosecutors appear to struggle with this concept because it requires the prosecutor to disclosure unfavorable evidence, including information that tends to impeach a police officer's testimony. When a prosecutor fails to provide access to evidence, reversal of a conviction, dismissal of the charges, or suppression of relevant evidence are available options depending upon the facts and circumstances of the violation.

Confrontation Clause

The Confrontation Clause of the Sixth Amendment to the United States Constitution provides that "in all criminal prosecutions, the accused shall enjoy the right...to be confronted with the witnesses against him." This guarantees the right is to have a face-to-face confrontation with witnesses who are offering testimonial evidence against the accused at trial. The Confrontation Clause is an issue in cases where laboratory personnel are unavailable as well as the rare case where a police officer retires or transfers to a different police department before the case proceeds to a jury trial.

Continue to Scientific Defenses: Winning a Not Guilty Verdict for an Innocent Client