The Science Behind Breathalyzer Testing

If you have received a DWI or DUI in the state of Minnesota, you will have to blow in a breathalyzer called the DataMaster. The DataMaster is used by law enforcement agencies for testing how much alcohol someone has consumed. The DataMaster measures your BAC or blood alcohol concentration. The driver provides two breath samples once taken into custody at the corrections center. Law enforcement looks at both breath samples and uses the lower value rounded to the nearest hundredths. If the sample is over the .08 legal limit, then the driver will be facing a DWI or DUI charge.


The first thing to occur is the driver will be asked to blow into a breathalyzer. The DataMaster requires a lung sample for testing purposes. This means the driver will have to blow a sufficient amount of air into the device for it to analyze the air sample accurately.

Prior to breath samples, law enforcement must observe the driver at least for fifteen minutes. The rationale behind this is that alcohol in the mouth can lead to inflated test results. Other errors can occur by the test subject burping, belching, vomiting that might inflate the results. If the test is not administered properly, there could be a challenge with your case.


The DataMaster uses a technology referred to as infrared spectroscopy. This analyzes the breath sample. The device generates an infrared light through the sample and measures the amount of light. The light is then absorbed by the alcohol in the driver’s breath. Therefore, the more alcohol present, the more light is absorbed.


The DataMaster uses a formula to do a conversion of alcohol in the breath to determine the blood alcohol concentration. The premise is there is a predictable ratio of alcohol in the breath to blood. Known as Henry’s Law, it predicts if alcohol is dissolved in blood, the concentration of the alcohol in the driver’s breath will be proportional to its concentration in the blood.


The BAC level will be generated on the device and a printout will be printed for record keeping. The results can be used against you in court and/or affect your license privileges. Minnesota is an implied consent law which means by operating a motor vehicle in the state you have consented to a chemical test of breath, blood, or urine to detect alcohol or drugs in your body.


In the State of Minnesota, a .08 percentage or higher is considered legally intoxicated for the purposes of driving. However, the drivers can face consequences for BAC levels below this, especially if their driving ability is impaired. Under Minnesota Statute 169A.20.1 Subdivision 1, it is a crime for any person to drive, operate or be in control of motor vehicle while under the influence of alcohol.


Regular maintenance and calibration are crucial for the accuracy of the DataMaster. Law enforcement has to make sure that the device is working properly and producing accurate findings. If a breathalyzer is improperly calibrated or maintained, then it could not produce accurate readings. The reason why there is uncertainty with readings is because the DataMaster gives estimates of your blood alcohol concentration indirectly through breath readings, so calibration is necessary. Under lab conditions there is an error rate of less than five percent, but the test is never performed in lab conditions.

While the DataMaster is an important tool for law enforcement, the results can be challenged in court. Considerations like improper use, calibration issues, and the driver’s physiological conditions can affect the accuracy of the DataMaster readings. If you have a DWI, you might encounter these possibilities when obtaining results. Make sure to get the right legal help for your case. Call our office (507-625-5000) or complete our contact form to speak to one of our attorneys.

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