Preliminary breath test: when is a breath test not a breath test?


Preliminary, or, portable, breath test

At present, the preliminary breath test, or, PBT, is a screening test authorized by Iowa Code § 321J.5 for the purpose of determining whether officers have reasonable grounds to believe someone is impaired to invoke implied consent. It is a screening tool—and its test result or even whether it is “positive” for alcohol is not admissible on the issue of intoxication before the jury.

The relevant code section reads, in part, that:

“When a peace officer has reasonable grounds to believe that [drunk driving or a motor vehicle collision has resulted in injury or death] the peace officer may request that the operator provide a sample of the operator’s breath for a preliminary screening test using a device approved by the commissioner of public safety for that purpose.” Iowa Code § 321J.5.

There are currently 13 such approved hand-held devices, including four machines produced by Intoximeters, Inc. (“Alco-Sensor”) and five made by CMI, Inc. (“Intoxilyzer”).

All of these machines are portable—in fact, the Department of Public Safety has pivoted from the codified designation of PBTs—called preliminary breath tests—to calling them portable breath tests.


However, they are more preliminary than portable under the law. As stated above, the PBT is inadmissible on the issue of intoxication before the jury:

“The results of this preliminary screening test may be used for the purpose of deciding whether an arrest should be made or whether to request a chemical test authorized in this chapter, but shall not be used in any court action except to prove that a chemical test was properly requested of a person pursuant to this chapter.” Iowa Code § 321J.5(2)(emphasis added).

Prosecutors believe that a PBT refusal is not a result and will attempt to offer a refusal before the jury.


But when a test subject either refuses or provides a PBT test result over the presumptive level of intoxication, which is .08 g ETOH/210 L breath, and, along with other observations, ultimately contributes to reasonable grounds for a law enforcement officer to believe that a motorist is impaired, that officer can invoke implied consent and detain the driver for another breath test at the stationhouse pursuant to Iowa Code § 32J.6, the evidentiary Datamaster DMT breath test.


Thus, there is a difference between the preliminary breath test, or, PBT, and the evidentiary Datamaster DMT, or, evidentiary breath test. That's why the PBT is not really evidence and why many people ask, "when is a breath test not really a breath test?" Good question, indeed.

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