Understanding the Reliability of Breathalyzers in DUI Cases

Breathalyzers have become synonymous with DUI (Driving Under the Influence) enforcement, serving as a quick and convenient tool for law enforcement officers to identify potential drunk drivers. However, their reliability has been debated, and faulty readings have raised concerns about accuracy.

Breathalyzers: A Double-Edged Sword

Breathalyzers are considered a go-to tool for law enforcement when they have suspicions of an individual driving under the influence of alcohol. These portable devices measure a person’s blood alcohol concentration (BAC) by analyzing the alcohol content in their breath. While they are famous for their ease of use and rapid results, breathalyzers are not infallible, and their reliability can be compromised.

The Case of Faulty Breathalyzers in Philadelphia

Recent Philadelphia, Pennsylvania events serve as a stark reminder of the potential issues with breathalyzer readings. In this case, between 500 and 1,000 DUI cases may be affected due to faulty readings from improperly calibrated breathalyzer units. Breathalyzers require annual calibration to ensure their accuracy. When these units are not calibrated correctly, individuals may receive elevated readings, indicating impairment, even when not impaired.

Inherent Inaccuracy of Breathalyzers

Studies have raised concerns about the inherent inaccuracy of breathalyzers, leading to questions about their reliability as a sole indicator of impairment. For instance, a survey conducted by the Wisconsin State Laboratory of Hygiene found that only 33 percent of breath test results correlated with blood tests from the same subjects. This significant margin of error can have real-life consequences for individuals facing DUI charges.

Court Cases Overturning DUI Convictions

In some cases, courts have overturned DUI convictions due to the limitations of breathalyzers. The New Jersey case of State v. McGinley highlights the complexities surrounding breathalyzer reliability. Four drivers convicted of DUI were acquitted based on various factors, including:

• Blood-Breath Ratio: Breathalyzers use a 2100/1 blood-breath ratio as an average measurement. However, this ratio can vary significantly among individuals, leading to potential inaccuracies.
• Temperature: The temperature of the breathalyzer device can affect test results.
• Body Temperature: An individual’s body temperature can impact breathalyzer readings.
• Blood Composition: Factors like hematocrit levels can influence test outcomes.