As Atlanta DUI lawyers at George C. Creal, Jr., P.C., Trial Lawyers, we often see cases where breath test results are presented as ironclad evidence of intoxication. However, these results are estimates, not absolute truths, and are subject to numerous variables that can impact their accuracy. In this post, we'll explore the key variables affecting breath tests in Georgia DUI prosecutions, drawing on state statutes and appellate decisions. Our goal is to shed light on how these factors can create reasonable doubt and strengthen defenses for our clients. If you're facing DUI charges, visit www.georgialawyer.com to learn how we can help.
Breath Tests as Estimates: The Foundation of Georgia DUI Law
Under Georgia law, a person commits DUI per se if their alcohol concentration is 0.08 grams or more within three hours of driving, as measured by blood or breath (OCGA § 40-6-391(a)(5)). "Alcohol concentration" is defined as grams of alcohol per 100 milliliters of blood or per 210 liters of breath (OCGA § 40-1-1(1)). This statutory framework assumes a standard conversion ratio, but breath tests are inherently variable, leading to potential inaccuracies. Georgia courts have recognized that the admissibility of breath test results is governed strictly by statute, ensuring compliance with approved methods and equipment (Brannan v. State, 261 Ga. 128 (1991) – holding that breath test admissibility is controlled exclusively by OCGA § 40-6-392).
Variables in breath testing fall into two main categories: machine variables and human variables. Understanding these can be crucial in challenging the state's evidence beyond a reasonable doubt.
Machine Variables: Issues with the Device Itself
Machine variables relate to the breath testing equipment, such as the Intoxilyzer 9000 commonly used in Georgia. These include:
- Radio Frequency Interference (RFI): External signals from radios or cell phones can interfere with readings. Georgia rules require devices to detect and invalidate tests affected by RFI (Ga. Comp. R. & Regs. r. 92-3-.06).
- Calibration and Maintenance: Devices must be calibrated quarterly and maintained properly. Failure to do so can render results inadmissible (State v. Kampplain, 223 Ga. App. 16 (1996) – ruling that disengagement of required components violates statutory requirements, making results inadmissible).
- Component Integrity: All manufacturer-prescribed parts must be attached and functional (OCGA § 40-6-392(a)(1)(A)). In cases like State v. Hunter, 221 Ga. App. 837 (1996), courts excluded evidence when devices lacked essential components, emphasizing strict compliance.
Prosecutors must prove the device was in good working order; any lapses can create reasonable doubt about the test's reliability.
Human Variables: Physiological Factors Affecting Accuracy
Human variables arise from individual differences and can significantly influence breath test results. These include:
- Breath Temperature: Higher breath temperatures can inflate readings, as alcohol volatility increases with heat. Georgia devices do not adjust for this, potentially leading to overestimations.
- Breathing Patterns: The length and depth of the breath sample matter. Longer blows can yield higher readings, as alveolar (deep lung) air has higher alcohol concentrations. Courts have noted officer discretion in sample collection can affect outcomes (see discussions in appellate briefs challenging breath test protocols).
- Hematocrit Levels: This measures red blood cell concentration in blood, which can vary and impact how alcohol is distributed, though less commonly litigated in Georgia.
- Lung Physiology: Factors like lung capacity or respiratory conditions can alter breath composition, affecting the sample's representativeness.
- Partition Ratio: Georgia law assumes a 2100:1 blood-to-breath ratio for conversion (OCGA § 40-1-1(1)). However, individual ratios vary (e.g., from 1700:1 to 2400:1), meaning the test might overestimate or underestimate true blood alcohol levels. While the statute fixes this ratio for per se prosecutions, evidence of variation can rebut presumptions of impairment in DUI less safe cases under OCGA § 40-6-391(a)(1) (Lattarulo v. State, 261 Ga. 124 (1991) – upholding the statutory presumption but allowing challenges to test accuracy where relevant).
In practice, prosecutors may move to exclude evidence of these variables unless the defense proves they specifically affected the result. However, this inverts the burden of proof—the state must prove guilt beyond a reasonable doubt, not the defense disprove the test (OCGA § 16-1-5). Georgia appellate courts have reinforced that defendants can introduce evidence raising doubt about test accuracy without proving exact deviations (Penny v. State, 248 Ga. App. 772 (2001) – penalizing the state for failing to preserve potentially exculpatory evidence).
Challenging Variables in Court: A Defense Perspective
In a notable Georgia appellate challenge (e.g., the brief in David Mark Smith v. State, appealed in 2005), experts testified on how unaccounted variables like breathing patterns and partition ratios undermine breath test reliability. The defense argued that concealing lower initial readings violates due process, citing Brannan v. State for statutory control over admissibility.
Unlike presumptions in some states, Georgia's OCGA § 40-6-392(b) allows a rebuttable presumption of intoxication from test results, but only if the test complies with all requirements. Defense attorneys can use human variables to rebut the State Administered Breath Test result (Young v. State, 275 Ga. 309, 565 S.E.2d 814 (2002)("An accused may always introduce evidence of the possibility of error or circumstances that might have caused the machine to malfunction. Such evidence would relate to the weight rather than the admissibility of breathalyzer results.")
Practical Implications for Georgia DUI Defense
These variables highlight why breath tests are not infallible. Don't let a breath guess send you to jail for a DUI. At George C. Creal, Jr., P.C., we scrutinize every aspect—from machine maintenance records to physiological factors—to build robust defenses. We've successfully challenged tests by showing non-compliance or inherent inaccuracies, often leading to reduced charges or acquittals.
If you're facing DUI charges involving a breath test, don't assume the results are unbeatable. Contact us at George C. Creal, Jr., P.C., Trial Lawyers, via www.georgecreal.com for a consultation. Our Atlanta DUI lawyers are committed to protecting your rights with expert analysis grounded in Georgia law. Stay informed—subscribe to our blog for more on DUI defense strategies.
Note: This post is for informational purposes and based on legal principles as of our last update. For recent developments, consult official sources or an attorney.