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.

Breath, Blood and Urine Testing

Breath, blood and urine testing all have certain advantages but also suffer from various weaknesses. Unfortunately, most Michigan DUI lawyers do not understand how these tests work, and they lack the advanced training necessary to proficiently attack the forensic evidence in a drunk driving case.

Breath Testing

Advantages: Breath testing is safe and unintrusive. There is virtually no risk of harm or infection to the subject being tested. Breath testing is fast and inexpensive, and evidential breath testing machines are designed to last for an extended period of time before replacement.

Disadvantages: Breath testing is an indirect form of testing for bodily alcohol levels. This means that a breath test is only circumstantial evidence of bodily alcohol content, even though it is frequently treated as direct evidence. As the body eliminates alcohol, a small portion of the alcohol is released through exhaled breath. This tiny amount of alcohol can be measured by a breath machine, and it provides an accurate estimation of the person's blood alcohol level in only the majority of cases. The amount of alcohol in a person's expired breath differs from individual to individual. Statistically, some people will provide a test sample that measures less than the true blood alcohol level. Between 3% and upwards of 20% of the public will provide a breath sample that measures higher than the true blood alcohol level. In a statistically small number of cases (but still relevant for evidential purposes), a person's breath alcohol score may be upwards of four times higher than the blood alcohol level, giving the impression that an objectively sober indvidual is extremely intoxicated.

Breath testing relies in large part on the proper maintenance of the breath machine, proper administration of the test, and proper screening of the breath test candidate. Maintenance, administration and screening is left almost entirely up to the local police department and the police officer performing the test. Michigan police officers are poorly trained in the area of breath testing. They are run through a quick class that details how to run a subject test and how to run a simulator test. The Michigan State Police have opted to omit almost all information about how breath testing works to the police officers that they train statewide to avoid permitting cross-examination on the scientific weaknesses that persist with breath testing.

Certain factors are known to cause elevated breath test results. If a person has a fever or higher than average breath temperature, the amount of alcohol will be perceived as being higher because the breath machine is set to accept a breath sample at specific temperature. Police officers experience this problem first hand when a simulator test goes bad and heats the testing solution too much. Officers will record a liquid/gas measurement of .08 repeatedly with a set mixture and suddenly have a breath simulator test register a .16. The amount of alcohol in the solution has not increased but because of the temperature difference, the machine perceives a higher breath score.

Another factor that is known to affect the accuracy of a breath test is the introduction of extraneous forms of alcohol. Because the breath machine is designed to measure microscopic amounts of alcohol from the deep lung air, any extraneous alcohol will result in a dramatically higher breath test result. Taking a small sip of low alcohol content beer, spitting it out and blowing into a breath machine will produce a breath result that would appear to indicate high levels of alcohol poisoning, even though the person actually has no alcohol in his or her body. Police officers would never invite a person to take a swig before testing, obviously, but this becomes a real problem when a person belches or if the person suffers from Gastroesophageal reflux disease (GERD). The tiny amount of alcohol introduced from the stomach gases can dramatically alter a breath test. This applies equally to trapped mouth alcohol that might be blown out during a breath test for people wearing dentures, a retainer or a tongue ring.

Finally, breath testing does not specifically test for alcohol, and this is a serious problem for people who have other chemicals in their body. Acetone, toluene and other organic compounds measure as if they are alcohol. These chemicals can be found in paint and paint thinners as well as a host of other industrial solvents. These chemicals can be absorbed through the skin or inhaled, and even in tiny amounts, these chemicals will create an effect that magnifies the amount of perceived alcohol in the breath sample. Diabetics will actually generate acetone and isopropanol naturally, particularly if the diabetic has consumed alcohol beverages since alcohol tends to interfere with insulin and glucose levels.

Continue to Blood Testing