Breathalyzer Reliability in Montgomery County DUIs

When law enforcement officials pull people over on suspicion of driving while under the influence, they often use breathalyzer machines. Below, a Montgomery County DUI lawyer discusses breathalyzers in substantial detail, including how reliable they are and potential ways they might give incorrect results. To learn more information about breathalyzers in Montgomery County, call and schedule a consultation with a Montgomery County DUI lawyer.

Reliability of Breathalyzers in Montgomery County

Breathalyzers are not the most reliable instruments. There are some presumptions that go into the administration of breathalyzer testing that force it to be kind of an inaccurate test.

What a breathalyzer test is measuring is your blood alcohol content, rather than your breath alcohol content. It does that by measuring the amount of alcohol that you exhale in a deep, long blow. It then multiplies that that by a partition ratio, which is a conversion ratio that converts a breath alcohol reading into an estimate of blood alcohol content.

That partition ratio is a one-size-fits-all ratio for everybody. It doesn’t matter whether you’re a 4’10” 85-pound woman or a 6’11” 350-pound man. The reality is that individual partition ratios are going to vary significantly across gender, height, weight, Body Mass Index (BMI) and many other different factors, which means that they physiological markers that make each person unique are also going to contribute to a slightly different partition ratio for each person. That is, the amount of alcohol in the bloodstream relative to the amount of alcohol exhaled is going to vary between individuals.

Even assuming that the test procedures are perfectly followed, if the machine is perfectly calibrated, that the solution the machine uses to calibrate is perfectly done, the fact that we’re using a single partition ratio for everyone in the population is inherently going to make the test itself inaccurate. All of these individual factors create additional layers of inaccuracy that can compound the inherent inaccuracy of the testing.

Potential False Positives or Inaccurate BAC Scores

There are a couple of ways that breathalyzers can result in false positives or inaccurately high BAC scores.

  1. Size and Sex: Small and very underweight females can result in the partition ratio that we currently use being too high for you. You will often see small female drivers blowing much higher than their actual true blood alcohol content because of that false partition ratio.
  2. Poor Test Administration: Before you blow into a breathalyzer, an officer is required to closely and continuously observe you for 20 minutes to make sure you don’t burp or belch or regurgitate or do anything else that can put stomach alcohol into your mouth. That mouth alcohol can result in an unusually high breath alcohol content. That can be one of the things that lead to false reading. Improperly Calibrated Machines: If the standard simulator solution is being made incorrectly and has a wrong alcohol concentration then the calibration of the machine will be adjusted accordingly and result in unusually high or improper reading

Important Issues Regarding Calibration of Breathalyzers in Montgomery County

The Maryland Code requires that machines are certified, and then they’re re-certified periodically (usually every six months or a year, depending on the machine in question). Additionally, the machine supposed to run a self-calibration at every test.

The machine has a standard simulator solution, and that solution is made to be 0.08 alcohol content. It will test that solution before and after every evidentiary breath test to make sure that the machine is still reading in the calibrated range. The statute requires that it test that solution that that test must be within 10% so to test this solution if it’s supposed to be a 0.08, the solution must read somewhere between a 0.072 and a 0.088 for it to be a validly admissible test.

Are Government Experts Aware of Potential Breathalyzer Issues?

Government experts are absolutely aware of the issues and inaccuracies involved with the use of breathalyzer results as evidence. Anyone who has looked at breathalyzer techniques has to be aware of all these issues, and reason that they continue to use these results as evidence is because DUI is such an integral part of the court system that if we really go back to basic science on these it would make DUI a much more difficult to prove for the prosecution.

Challenging Breathalyzers in Montgomery County Court

Erroneous or inaccurate breathalyzer results can absolutely be challenged in court. That’s going to be one of the main areas of defense for a potential for DUI case where there is a breathalyzer or a blood test. It almost always involves challenging the admissibility or reliability of that test. That can be a challenge that the test wasn’t done correctly, or it can be a broader challenge.