Breathalyzer devices are machines - and machines fail. Calibration logs, maintenance records, operator certification, and observation period compliance are all subject to challenge in DUI cases. This checker identifies the specific accuracy issues in your breath test administration that a DUI attorney can challenge.
An experienced DUI attorney subpoenas calibration records, maintenance logs, and operator certifications to build a complete breathalyzer challenge. Free case review - no obligation.
Breathalyzer devices measure alcohol in breath and convert that measurement to an estimated blood alcohol concentration using a fixed partition ratio of 2100:1 - meaning the device assumes everyone's breath-to-blood ratio is exactly 2100:1. In reality, partition ratios vary from approximately 1700:1 to 2400:1 across individuals. A person with a lower-than-average ratio who blows a 0.09% result may have an actual blood BAC below 0.08%.
Add to this the required maintenance protocols, calibration schedules, and operator training requirements - all of which are frequently not followed perfectly - and you have a device with a documented margin of error of plus or minus 0.01% at minimum. When your result is close to 0.08%, that margin of error matters enormously. A DUI attorney requests the full calibration history of the specific device used in your case through discovery. Pair this analysis with the BAC calculator for a rising blood alcohol analysis and the full DUI defense evaluation for a complete case assessment.
Before administering an evidentiary breath test, officers in virtually every state must continuously observe the subject for 15 to 20 minutes to ensure no mouth alcohol contamination. Mouth alcohol - from a recent belch, burp, vomit, or use of mouthwash - can cause the device to read significantly higher than actual blood alcohol. If the officer left the room, was distracted, or failed to document continuous observation, the test result is challengeable. Courts have excluded breath test results solely on observation period failures.
A thorough breathalyzer challenge requires: the device's calibration log for the 12 months surrounding your test, the maintenance and service records, the operator's certification documents and training records, the agency's testing protocols, and the actual printout from your specific test showing all readings. Most of this is obtained through a discovery request or public records request. Some jurisdictions require the state to produce these records automatically before trial; others require a specific motion. An experienced DUI attorney files these requests immediately after retention.