Just a Number on a Piece of Paper: Issues Affecting the Reliability of Blood and Breath Test Results

We know what you’re thinking: “My blood alcohol test came back above the legal limit, so I’m screwed.” In DUI (Driving Under the Influence) cases, blood and breath tests are often seen as indisputable evidence of intoxication. However, what many people may not realize is that these tests are not infallible and can be subject to errors and inaccuracies. We have a saying in our office: “It’s just a number on a piece of paper.” It is crucial to understand the potential pitfalls of relying solely on blood and/or breath test results in DUI cases. Here’s why these tests can be inaccurate and how it can impact your case’s defense.

  1. Variability in Breathalyzer Devices: Breathalyzer devices are calibrated to provide accurate readings under specific conditions. However, factors such as environmental conditions, device calibration, and operator error can affect the reliability these tests. For example, if a breathalyzer device is not properly calibrated or maintained, it may produce inflated test results, leading to false accusations of intoxication or more severe DUI charges.
  1. Mouth Alcohol: Breathalyzer tests rely on the assumption that the air expelled from the lungs is representative of the alcohol content in the bloodstream; that it is deep lung air. However, residual alcohol in the mouth or throat (mouth alcohol) can be read by the breath tester as deep lung air, producing an artificially high and inaccurate result. Factors such as recent consumption of alcohol, the use of mouthwash or breath fresheners, or even certain medical conditions can contribute to the presence of mouth alcohol which is incorrectly read by the testing equipment as being an accurate breath test result.
  1. Medical Conditions and Diet: Certain medical conditions and dietary factors can affect the accuracy of breath test results. Conditions such as diabetes can produce acetone or other substances in the breath that may be falsely interpreted as alcohol by breathalyzer devices. Low-carb or ketogenic diets can result in the production of ketones, which can also interfere with the testing and lead to inflated test results.
  1. Improper Blood Sample Handling: Blood tests, often considered more reliable than breath tests, are not immune from errors. Improper collection, storage or handling of blood samples can compromise the integrity of the sample and lead to inaccurate test results. Factors such as contamination, improper storage temperature or insufficient mixing of anticoagulants can all contribute to errors in the blood alcohol analysis.
  1. Lab Errors and Contamination: The process of analyzing blood samples for alcohol content involves multiple steps that are intricate in nature, from sample preparation to analysis using specialized equipment. Each step presents opportunities for errors or the introduction of contamination into the results. Laboratory errors, such as malfunctioning equipment or cross-contamination between samples can undermine the reliability of blood test results.
  1. Individual Variability: The way any of us metabolize alcohol depends on various factors such as weight, gender, and tolerance levels. These variables can influence how quickly alcohol is absorbed and eliminated from the body. This is crucial to understand when analyzing the results and reliability of blood and breath test results.

Inaccurate blood and breath test results can have serious legal consequences for individuals facing DUI charges. A false positive, or an inflated test result can lead to unwarranted arrests, license suspensions, jail time, and other penalties for those arrested for DUI. It is essential to recognize the limitations and potential pitfalls of both blood and breath tests when defending someone accused of DUI. Equally as important, you must find a lawyer who understands these issues, and how to challenge them in a courtroom. At St. Louis and Huffman we are committed to challenging the validity of blood and breath test results to protect the rights of our clients. If you or a loved one have been arrested for DUI, don’t hesitate to reach out to us for a consultation.

About the author:

Ryan Huffman is a trial lawyer with a background in defending clients accused of crimes. As a Partner in St. Louis & Huffman, he represents individuals accused of DUIs, misdemeanors and felony offenses at courts in Tucson, Pima County and throughout Arizona.

Ryan set an office record for the most trial wins in the shortest period of time by winning three DUI trials in a row in an eight-week period – not guilty verdicts across the board in all three trials, which included a reported blood alcohol concentration as high as .213. Ryan has vigorously represented accused individuals throughout all stages of litigation, including trials and appeals. His experience includes both misdemeanor and felony criminal matters. He has a particular familiarity with motion practice, seeking to have his clients’ cases dismissed prior to trial, and is passionate about advocating against unethical police tactics and procedures. Not afraid to take a case to trial, Ryan successfully negotiated a plea to probation midtrial when his client would have been required to serve life in prison if convicted.