Understanding the Difference between a Chemical Test and a PAS Test for DUI


There is a prevailing confusion as to what constitutes a DUI stop and a DUI arrest. The confusion seems to be greatly anchored on the use of a preliminary alcohol screening test, or PAS Test, and the use of a chemical breath test. While the two tests are nominally different, they are both tests that involve the measurement of alcohol levels based on breath analysis.

So, What Is The Difference?

It should be noted that preliminary alcohol screening tests are not only limited to the use of Breathalyzer devices. Some other tests include the one leg stand test, the horizontal gaze-nystagmus test, and the walk-and-turn test. These tests are performed in order to ascertain sobriety on the individual suspected of DUI. In simple terms, these tests are used by law enforcement agencies to rule if there is probable cause to believe that the person was driving under the influence. Understand that PAS test is a field sobriety test.

Now, here’s the catch. Field sobriety tests are not mandatory. Individuals who are stopped by law enforcement agencies may choose not to perform these field sobriety tests, including PAS testing. Additionally, law enforcement officers must be able to inform the individual of his right to refuse taking the PAS test. It should be made clear that field sobriety tests are merely tools which a law enforcement office can use to determine if there is the presence of a valid probable cause to arrest the individual on suspicion of a DUI offense.


Once the law enforcement officer makes the arrest, however, the individual no longer has the right to refuse a chemical breath test. Under the California Implied Consent Law, for example, an individual who was lawfully arrested on suspicion of DUI is legally obliged to take a Breathalyzer test on the spot or an alcohol blood test upon arrival at the law enforcement agency office.

In short, preliminary alcohol screening tests are conducted before any DUI arrests are made. Chemical alcohol tests are done after legally executing a DUI arrest either on the spot or in the precinct. It is therefore a must to understand that as a field sobriety test, individuals have the right not to subject themselves to such tests. However, this does not guarantee that the law enforcement officer will not execute an arrest. This is a common case among many PHD who end up at the hands of law enforcement officers quite often for DUI.

If you are still confused about this, then visit americanguineahogassociation.org for a more detailed explanation on the differences between a PAS and chemical tests used in DUI cases.

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