As a Seattle and Tacoma DUI Attorney I've been handling DUI cases for ten years now – half that time as a DUI prosecutor, the other half as a DUI defense lawyer. Most DUI cases follow a pattern - the driver is stopped for a traffic infraction; during his initial investigation the cop smells alcohol and the driver admits to having "a couple;" the cop orders the driver out of the vehicle and asks if the driver will submit to "voluntary" Field Sobriety Tests ("FSTs"), which the driver does. At this point, fully intending to arrest the driver anyway, the cop asks her if she'll submit to a Portable Breath Test (PBT) using a small hand-held device.
Should you take this test? The answer is simple: NO. Here's why.
You Don't Have To, and If You Refuse It Can't Be Used Against You.
Unlike the FSTs, if you refuse the PBT, the fact that you refused cannot be used against you at trial. It probably won't be used against you even in an evidentiary suppression hearing.
The difference between refusing the PBT and refusing the FSTs is that the prosecutor can use the latter as evidence of guilt against you at trial. (Refusing to submit to the BAC Breath Test at the station is specifically admissible as evidence under the Implied Consent Warning statute.) If you submit to the PBT, although the result cannot be used against you at trial, it can and WILL be used against you at a pretrial suppression hearing.
Even if the prosecutor tries to use the fact that you refused the PBT against you at that hearing, in my experience a judge will disregard this, and most cops are honest enough to admit they don't factor that into their decision to arrest.
The Cop Can Lie About the Result. And There's No Way to Prove Him Wrong.
I file a Motion to Dismiss for Lack of Probable Cause in every DUI case I have that gets set for trial, and I demand an evidentiary suppression hearing (called a "3.6" hearing) to argue that motion. If I can convince the court that the cop arrested my client, but didn't have probable cause to do so, then any evidence gathered after the arrest is suppressed, and the case is almost always dismissed.
If you submit to the PBT, however, and the result was over .08, that alone will defeat a motion to dismiss for lack of probable cause at that hearing.
And here's the kicker - if the cop says your PBT reading was over .08, there's no way to prove otherwise. That's because there's no printout of the result, and no record of it other than what the cop says in his report. The BAC test result at the station, on the other hand, produces a printed ticket, and is also recorded on the WSP breath test database.
There's also no way to determine whether or not the PBT device itself was reliable, or whether or not the cop followed all the required procedures, like there is with the BAC machine. Other than what the cop says. Do you think he's going to admit he did it wrong?
And just like a speeding ticket, the arresting officer often won't even tell the driver what the result of the PBT was. Guess what? There's nothing that says he has to. Sound fair?
Whether or not your PBT result is over the legal limit, which alone will meet probable cause, is totally up to the cop and his level of honesty. It's all up to the cop. Are you willing to bank the outcome of your case, and your future, on that? I'm not.
The PBT Result May Be the Only Evidence That Supports Probable Cause for Arrest.
Not only will a PBT result over the legal limit alone meet probable cause, I've had several cases where that's the ONLY reason the court found that the standard had been met.
I recently had a suppression hearing where I argued no probable cause for the arrest. In that case there was a PBT result, and it was over the legal limit. It was clear to me that without the PBT the cop lacked probable cause to arrest. It all came down to whether or not he followed all of the steps required for the PBT to be admitted. Because of that question, and before it was ruled upon by the court, I was able to negotiate a reduction to a lesser charge, which before the hearing the prosecutor was unwilling to agree to. My client was happy with the reduction. Had he declined the PBT test altogether, however, the case would likely have been dismissed.
I have yet to hear of a case where the cop let the driver go because the PBT result was under the legal limit. In fact, I've had several cases where the result was below the legal limit, and my client was STILL arrested for DUI. After 10 years I am convinced that you have nothing to gain by submitting to the PBT.
Your best defense of course is not to drink and drive to begin with. If you should find yourself in a situation where you've been pulled over after doing so, however, there's no reason to dig a deeper hole for yourself. To use a well-worn cliche from the '80's, When the cop asks you to volunteer for the PBT, just say no.