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In The Media :

What is a Portable Breath Test (PBT) in Illinois?

A “Preliminary Breath Test Device” or “PBT” means a portable device used to quantitate a breath analysis reading. 20 Ill. Adm. Code 1286.10. These devices are used by police officers in Illinois to obtain probable cause to arrest a person for Driving Under the Influence of Alcohol (DUI). A portable breath test is considered a Field Sobriety Test.


Breath testing is based upon Henry’s Law which states that if a gas and liquid are in a closed container, at a constant temperature, and in a state of equilibrium, the concentration of the gas in the air above the liquid is proportional to the concentration of the gas which is dissolved in the liquid. Breath testing uses Henry’s Law and other scientific principles to measure alcohol in a suspect motorist’s system.

A suspected drunk driver is requested to deliver breath into a breath testing device chamber from their lungs. This breath is sent into the device which measures the amount of alcohol blown into the machine. Through a series of calculations, the machine then returns a result.

Can the Portable Breath Test Result Be Used Against Me?

PBT results can be used against a defendant in Statutory Summary Suspension hearings or in DUI cases for probable cause to arrest only. 625 ILCS 5/11-501.5. It is important to note that a person must consent before being administered a PBT or the State may not admit the result. People v. Rozela, 802 N.E.2d 372. Unlike an Evidentiary Breath Test, the results of the portable breath test cannot be used against a person at trial.

If you are charged with a DUI in Springfield, Illinois, contact our DUI Defense Lawyerstoday at (217) 414-8889 for a free-initial consultation. To read more about breathalyzers, please view our Breathalyzer Defense Page.

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