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DUI Basics: What Is a PAS (Preliminary Alcohol Screening) Test?

By Daniel Taylor, Esq. on January 15, 2015 | Last updated on March 21, 2019

During a DUI stop, the results of a preliminary alcohol screening (PAS) test will often determine whether a driver is arrested or let go.

But there are some important differences between these preliminary alcohol tests and the testing of blood, breath, or urine following a DUI arrest.

What makes a PAS test different?

Probable Cause for DUI Arrest

During a traffic stop, if an officer suspects you may have been driving under the influence, he or she will be looking for the probable cause that's required to make an arrest (which may already be present, depending on the reason behind the traffic stop). Many times, however, an officer will place a suspected DUI driver through a series of field sobriety tests to determine whether he or she is intoxicated.

Like a field sobriety test, a PAS test -- typically a preliminary Breathalyzer test -- is used to determine whether there's probable cause for an arrest.

And like field sobriety tests, a PAS test can generally be refused by a motorist. Under Hawaii law, for example, a law enforcement officer is required to inform a driver that he or she may refuse to submit to a PAS test.

But what about "implied consent"? Many states have implied consent laws under which a person consents to sobriety tests by obtaining a driver's license or driving on the state's roadways. Under such laws, refusing a chemical or breath test following a DUI arrest can result in penalties, including fines and the automatic loss of a driver's license.

But because PAS tests are used to establish probable cause for an arrest, implied consent laws may not apply to PAS tests. California's implied consent law, for example, requires drivers to submit to a blood or breath test only after being lawfully arrested.

To learn more about DUI arrests and alcohol/drug testing of drivers, head over to FindLaw's section on DUI Law.

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