DUI Lawyer: can PBT be misused?

Good law enforcement officers investigating an Iowa DUI—called OWI here— do not use the preliminary breath screen, or, PBT, to confirm their subjective bias that impairment already exists.

An Iowa DUI investigation for Operating While Intoxicated begins with Phase One, Vehicle in Motion. If an officer believes that probable cause exists to believe that a motorist has committed a traffic violation—or, alternatively, that reasonable suspicion to believe that a more complex crime, for example, Operating While Intoxicated, is occurring, he or she may conduct a traffic stop.

In Phase Two screening, an officer will ask a divided attention, compound question by requesting license, registration, and insurance. If the officer observes the odor of alcohol, slurred speech, and bloodshot, watery eyes, the officer will inquire about alcohol consumption as well as points of departure and destination.

In Phase Three, officers will request standardized field sobriety testing, or, SFSTs, which are ostensibly voluntary. The SFSTs usually include the horizontal gaze nystagmus test, or, HGN, the Walk and Turn, or WAT, and the One Leg Stand, or, OLS.

After these physical agility and divided attention tests, if the officer believes reasonable grounds exist to conclude impairment, he or she may request a preliminary breath test, or, PBT, using a portable breath test device that tests ONLY for ethanol.

Here is where human bias comes into play even for highly trained officers. The officers are trained to get to this “next level” in the process, e.g., Iowa Code § 321J.5, if they already believe they have reasonable grounds to believe the subject is impaired enough with ethanol to request a PBT.

That doesn’t necessarily mean they have the reasonable grounds necessary to invoke implied consent—and it certainly doesn’t mean they have probable cause to make an arrest. But some officers treat the preliminary screen either as superfluous or merely confirmatory.

I have seen the following repeatedly:

1.     Officers will often tell a DUI suspect that the PBT is “not admissible in court.” Partially true. Partially false. It is admissible in a pretrial proceeding to determine whether reasonable grounds exist to invoke implied consent or make an arrest. It is not, however, admissible on the issue of intoxication at jury trial. In fact, Iowa Code § 321J.5(2) states that “the results of this preliminary screening … 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.” So they can be used in court—just not at jury trial.

2.     Some officers will tell a DUI suspect that the PBT is “just to confirm whether the test subject’s impairment I’m seeing is caused by alcohol or ‘something else.’” Absolutely false—and completely fraught with confirmatory bias. The standardized field sobriety tests are subjective field tests—not laboratory tests. Officers must have sufficient reasonable grounds to request a preliminary breath test but it can also rule out impairment if they’re being fair minded. To suggest that the decision has already been made and the PBT is just going to confirm the officer’s bias misuses it—treating it much like a “reverse drug detector” or other medical instrument for which it is not certified. Officers who do not run afoul of this confirmatory bias instead just say, “it’s just another tool to see where you’re at.” This is a more accurate—if vague— assessment.

3.     Some officers will often say they have enough probable cause to arrest a subject before they ever request an evidentiary breath sample using the Datamaster DMT certified for use by Iowa Department of Public Safety. This is pretty bold and can present a quandary if they're wrong. The Datamaster DMT is typically the only scientific evidence in the case. Everything else, including the officer’s  observations regarding standardized field sobriety tests, is subjective. Officers need not make such an arrest. They can detain temporarily under Iowa Code § 321J.5 for purposes of invoking implied consent and seeking a bodily specimen for chemical testing. If they turn out to be wrong, they can release the subject.

4.     Officers will sometimes, not as frequently as the above instances, inaccurately advise a DUI suspect that the Datamaster DMT is exclusively administrative—that they have made their decision to arrest the subject and the scientific test result is not relevant to anything but the Iowa DOT administrative revocation. False. In effect, the officer will have to reform his or her theory of the impairment if the only scientific testing in the investigation refutes their predetermined mindset. That usually means they will try to rehabilitate their investigation by asking for urine or blood. This is allowable but does suggest that the officer's assumptions were incorrect.

Are any of these fatal to the investigation and thus prosecution? Not necessarily and not usually if taken separately. But an experienced criminal defense lawyer practicing in the area of Iowa DUI, or, OWI, in the State of Iowa can examine all of the facts and circumstances in the case to determine if an officer has introduced fatal defects into the investigation.

Contact us for a free initial consultation if you are the defendant and have presented before an Iowa court magistrate or judge on the charge.