Breath Testing

What is it like taking a breath test in Glastonbury? On this page, we explain what the breathalyzer test is, how it works, and some common issues that occur with breath testing. If you have been charged with a Glastonbury DUI, you may be able to use this information to refute the results of a breath test. For more information, contact us.


In Glastonbury, law enforcement will often use breath testing as a way to obtain evidence against a driver for a DUI. The breath test machines, otherwise known as breathalyzers, use infrared light to detect alcohol on a person’s breath. As the person blows into the mouthpiece and the air travels into the device, the molecules will pass through beams of infrared light that can detect the absorption of ethanol in those molecules.

Henry’s Law

The testing of breath for alcohol is based on a science called Henry’s law. Henry’s law is defined as “the mass of a gas that dissolves in a definite volume of liquid which is directly proportional to the pressure of the gas provided that the gas doesn’t react with the solvent.” In other words, if a gas and a liquid are contained in a closed container, the concentration in the air above it is equal to the concentration in the blood.

Henry’s constant refers to the fixed constant of ratio given to the blood in the body. This constant is roughly 2100:1, meaning that the average concentration of alcohol in the blood to the air is around 2100 to 1. Unfortunately, there is no normal ratio that works as a constant for all body types since each body is different. Because of this, it is estimated that breathalyzers have up to .03% error or more.

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Breathalyzer Defenses

The breath sample results could be affected by the person’s body temperature. Even a slight change in body temperature could result in inaccuracies. Other inaccuracies could come from things like taking certain medications, having certain illnesses, or having diseases like diabetes.

The breathalyzer results can also be unreliable when the device is poorly maintained or calibrated incorrectly. These are two very viable defenses for a DUI. The administrator of the test must also be trained and certified in administering the test. If their certification is not up to date, the test could be thrown out.

Other factors that could affect the accuracy of the test are things like eating, vomiting, burping, or smoking just prior to taking the test. Issues like these can alter the breath sample. Lastly, in order for a breath test to be admissible in court, there must be two clear results that are within .02 in measurement from each other.

Under Connecticut law, each driver is considered to have implicitly consented to give a breath sample if requested by law enforcement. This is because of Connecticut’s implied consent laws. However, each person has the freedom to decline the test and face the consequence from the DMV of an automatic license suspension. The consequences of consenting may be even more serious, as the evidence from the breath test can be used to support the DUI case.

A good DUI lawyer will be able to find any errors or defenses in a DUI case. If you are looking for a DUI lawyer to represent you, or you have further questions regarding breath testing in Glastonbury, call Lady DUI to find out how we can help.

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