DUI Preliminary Alcohol Screening Test (PAS)

After you were stopped for a DUI and the officers decided they had a probable cause to go further, they likely ran you through a few roadside tests, called field sobriety tests, and they also may have informed you that you could take a preliminary breath test.

The preliminary breath test is often called the preliminary alcohol screening test or PAS, although the name varies from state to state. When the officers offered you this test, they may have informed you that taking the test might result in your release if the result was low enough and drugs weren’t also indicated. If the officers were doing their job right, they also explained that the PAS test is not the same as the mandatory test that you could still be required to take under your state’s implied consent laws. (See Mandatory Chemical Tests and Implied Consent.)

The PAS test result may have surprised you. Rates of absorption and elimination of alcohol from the body are tricky to compute; they vary considerably according to a number of variables. 

PAS tests, by definition, have been made possible because of the development of portable breath testing machines that would produce an immediate readout. Formerly, the police wouldn’t have any idea what your breath showed your BAC to be until they took the sample back to the police station, sent it to the state laboratory, and waited (sometimes weeks) for the result. Now, the machines used for the PAS are said to be as reliable as the machine used for the mandatory test (assuming you chose the breath test). In fact, at least one of the machines available for general use boasts equal reliability for PAS and the mandatory test under the implied consent law (the Dräger Alcotest 7410).

Even though the new machines are reliable, they must be calibrated regularly. If they aren’t, their results may not be admissible in court. Which machines were used in your case, and whether they were properly calibrated, will likely be a function for your state’s (and community’s) budget. For valuable information about these machines and some of the possible problems to look for, see Drunk Driving Defense, by Lawrence E. Taylor (Sixth Ed. Aspen publishers 2006, supplemented 2008) or California Drunk Driving Defense, by Lawrence E. Taylor (4th Edition (West Group 2009)).

Next, read about DUI Field Sobriety Tests.

Excerpted and adapted from Beat Your Ticket: Go to Court & Win, by David W. Brown (Nolo).

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