Georgia DUI Breath Testing’s Dirty Little Secret

Understanding Blood Breath Ratio Assumptions in DUI Breath Testing: Insights for Georgia Drivers

When facing a DUI charge in Georgia, understanding the intricacies of breath testing technology and the legal assumptions underpinning it is crucial. Central to this is the concept of the blood breath ratio (BBR), which significantly affects the outcome of breathalyzer tests. In this blog post, we’ll explore the blood breath ratio of 2100:1, its variability, and its codification in Georgia State law.

DALL·E 2024-05-13 10.04.30 - A scene depicting a person arrested for a Georgia DUI blowing into an Intoxilyzer 9000 in a jail environment. The setting is a typical police station

What is the Blood Breath Ratio?

The blood breath ratio (BBR) is a scientific estimate used to convert the amount of alcohol detected in one’s breath into a corresponding blood alcohol concentration (BAC). In DUI breath testing, a commonly used ratio is 2100:1. This means that for every 1 part of alcohol in the breath, there are approximately 2100 parts in the blood.

 Variability of Blood Breath Ratios

It's important to note that the 2100:1 ratio is an average, not a constant across all individuals. Research indicates that the actual BBR can vary between 1500:1 and 3000:1 in the human population. Several factors contribute to this variability:

  • Gender Differences: Women often have a higher BBR due to differences in body composition and metabolism rates compared to men.
  • Racial Variations: Studies have shown that racial and ethnic differences can influence metabolism and lung function, affecting the BBR.
  • Physiological Conditions: Factors like body temperature, lung health, and even the breathing pattern and length of breath at the time of testing can lower the BBR which is why police will encourage you to blow past the minimum required 4 seconds…”blow, blow, blow, blow, blow.” Pro-Tip: Hyperventilate before the breath test and always stop after 4 “blows.”

Legal Implications in Georgia

In Georgia, as in many other states, the assumption of a 2100:1 BBR is codified into law. OCGA 40-1-1(1)(“‘Alcohol concentration’ means grams of alcohol per 100 milliliters of blood or grams of alcohol per 210 liters of breath.”) This standardization simplifies prosecutions by providing a uniform measure across cases, but it shamelessly discriminates against individuals with a lower blood breath ratio and favors those with a high blood breath ratio.  As Julius Caesar famously said, “All Romans are equal but some are more equal that others.” In plain terms, this means that individuals whose natural BBR deviates from the assumed average might face inaccuracies in their BAC estimations.

How Georgia Law Addresses BBR Variability

Georgia law recognizes that breathalyzers are not infallible and provides mechanisms for challenging BAC results based on breath tests. Defense arguments often hinge on demonstrating how an individual’s unique physiological characteristics could render the breath test results inaccurate or misleading. Remember it is not a breath test, it is just a breath guess. 

For anyone facing a DUI charge in Georgia, it's essential to understand how the assumption of a 2100:1 blood breath ratio could affect your case. This standard assumption does not account for the biological diversity among individuals, potentially leading to significant legal ramifications. If you find yourself in such a situation, consulting with an experienced DUI lawyer like George Creal can provide you with the insights and representation needed to challenge inaccuracies in DUI breath testing.

For more detailed advice tailored to your specific case, contact George Creal’s office directly to schedule a consultation at 404-333-0706 or on the web at

This blog post aims to shed light on the technical and legal aspects of DUI breath testing, particularly focusing on the implications of the blood breath ratio assumption. It encourages a deeper understanding and proactive legal consultation for those affected by such DUI charges in Georgia.