Are DUI cases won and lost on alcohol breath testing? Well DUI defense lawyers are often asked why they are taking a particular drunk driving case to trial, when a breath analysis machine has produced a reading above the legal limit. What these drunk driving lawyers know, and what they hope to educate their juries about, is that the breath testing machines that are used in DUI and DWI arrests are subject to error even in the best of circumstances. Breath testing in drunk driving cases is far from perfect.
If you are facing DUI charges and you think your case is over because your breath tested above the legal limit, then you should get a DUI defense lawyer on your case. Turns out, much of DUI breath analysis evidence can be combated by an attorney who understands the science behind this type of testing.
Even alcohol breath testing in DUI cases has a history. It dates back to 1937, when Rolla Harger invented the "Drunkometer". This machine gave birth to an industry that has witnessed many new designs, each trying to improve on the reliability of its predecessor. However, even in our present era, every single breath analysis device is subject to mistakes. All breath-testing machines used in DUI and DWI cases make certain assumptions about the people being tested that may or may not be true. All of the drunk driving breath-testing machines are subject to human error, maintenance problems, interference from outside sources (such as radio frequency interference), and internal malfunctions.
Alcohol breath testing is an indirect way of determining blood alcohol content (BAC) or blood alcohol level (BAL). Many states have tried to get around the obvious problems associated with converting a breath alcohol level to a blood alcohol level by outlawing driving above a certain limit as determined by either a blood or breath test. DUI and DWI lawyers in most states confront laws that make it illegal to drive while under the influence of alcohol, or to drive with a blood or breath alcohol level of .08% or higher. The former is based on actual impairment; the latter is based only on the subject's alcohol level, without regard to whether or not they are actually feeling the effects of drinking alcohol. Talk to a DUI lawyer if you want to know how this pertains to your specific case.
IMPORTANT: Did you realize that in most states, the officer conducting the investigation is supposed to tell the DUI suspect that blowing into the PAS (Preliminary Alcohol Screening) device is optional? In practice, this is done inconsistently, at best. Breath testing for alcohol is typically accomplished either on a roadside test prior to arrest, or on a more stationary machine at the jail following arrest. The portable device, which is a little bigger than a pack of cigarettes, is called a Preliminary Alcohol Screening (PAS) test, or Preliminary Breath Testing (PBT) device.
SIDEBAR: The technology in the roadside PAS test is called "fuel cell" technology. This technology works by burning up the alcohol, which generates an electrical current that is measured and quantified with a numeric result. The technology in these roadside PAS tests is dubious at best. These devices do not have "slope" detectors, which are designed to guard against mouth alcohol causing an artificially high reading by detecting a negative slope (or sharp drop-off) in the alcohol level; they are not specific for alcohol, and are subject to error due to certain types of chemical buildup.
The technology used in the stationhouse breath testing devices is slightly more reliable, in that they do typically have slope detectors to guard against mouth alcohol contamination, but are subject to human, internal, and external error as well. The stationhouse alcohol breath testing machines may use a fuel cell, or an infrared system to measure alcohol levels. Where an infrared system is used, the breath sample is blown into a chamber, and an infrared beam is shot from one end to the other. The beam is absorbed by alcohol molecules (and other molecules in the same spectrum, unfortunately), and the amount the beam is diminished as it passes from one end of the sample chamber to the other is measured, and is expressed in a numeric value. The greater the amount of light that is absorbed from one side of the chamber to the other, the higher the reading on the machine.
With all these flaws in the breath analysis testing, it is so important to get a lawyer who specializes in DUI defense to work with you. Unfortunately for those who stand accused of DUI, DWI, or any other drinking and driving related offense, the ways in which the breath testing machines can be in error are many indeed. They include problems with mouth alcohol causing artificially high results, non-specificity to alcohol (where other compounds are mistaken for alcohol by the machine), radio frequency interference, calibration errors, human error, and more. Your lawyer will be able to combat breath-testing evidence and that could help you get a much better outcome in your case. Talk to a DUI LAWS attorney today for help with your DUI charges.