Breath Test Machine

Estimated reading time: 7 minutes

The government likes to call it a breath test. But do their machines fail the test of science? Is it reliable and scientifically valid?

DWI Attorney Thomas Gallagher shares insights from decades of challenging breath testing machines.

Breath Test Machine: unreliable

The simple fact behind Minnesota government’s machine is that alcohol vapor in a person’s breath blocks infrared light. The machines trap a person’s breath in a glass tube. Then, it sends infrared-wavelength light through it. And sensors on the other side of the tube detect how much of the infrared light made it through (was not blocked by … something).

The machine is based on the premise that alcohol blocks any infrared light that didn’t make it through. But many chemicals in breath other than alcohol can cause a false reading.

Trial by Machine: the Machine Age

Interferants

Scientists know that many factors can cause the machine to report an inaccurate alcohol level. And one of these is the presence of “interferants” in the subject’s body and breath. Thousands of common household and industrial (work) chemical products contain Volatile Organic Compounds (“VOCs”). VOCs absorb into the subject’s blood, and later dissipate from the person’s body. And VOCs dissipate out of the lungs and breath.

We call them “interferants.” They interfere with the operation of infrared breath alcohol machines. Interferants block the infrared light like alcohol molecules do. They cause a false reading for alcohol, because the machine thinks that they are alcohol (though they are not).

More false readings on breath test

The breath test machine is vulnerable to other problems:

• radio interference,
• inadequate observation periods by police,
• wrong dry gas cylinder installed as standard,
• mouth alcohol contamination, including acid reflux,
• diabetes & rapid weight loss (ketones, an interferant),
• environmental factors, during administration,
• other factors relating to subject person.

Defenses: police negligence

Motive: In addition, the law itself creates incentives police to label a person as a “refuser.” True or not, the label saves them time and work. They can then skip the breath test, to save time and work. And a police officer can also use the “refusal” label to punish a driver. Because penalties are more severe for refusal, than for providing a sample with over 0.08 alcohol concentration.

So the law prompts police with a powerful temptation to abuse their discretion, consciously or not, and call someone a “refusal.”

Not only that, the State actually trains police to blame the driver, when their machine malfunctions. These malfunctions include mouth alcohol, blocked breath tubes, wrong dry gas cylinder, etc. But rather than try to troubleshoot the machine malfunctions and police errors, just blame the driver. However, a good DWI defense attorney can spot this.

Defenses: law & procedures

General themes of DWI litigation are:

1. the government valuing expediency above justice; and
2. efforts by government to ignore truth, hide truth, and deny drivers access to truth.

This contradicts a core purpose of the court: “the search for the truth.” There are many examples of this. Yet thousands of innocent Minnesotans suffer as a result of false DWI “evidence” every year.

How does the government deliberately try to hide the truth? The destruction of exculpatory evidence is one way. Curtailing the right to pretrial discovery of evidence in “implied consent” driver’s license cases, is another.

Breath Test vs Blood & Urine Tests

Minnesota has three types of chemical tests for alcohol in drivers. And each requires a search for a sample of the subject’s bodily fluid or gasses.

The three types are tests of a breath, urine or blood sample.

A lab must be test urine and blood samples. And that takes time. It also costs more money for the state than a breath machine test. For more on the urine test, see:

Minnesota urine test.

Two breath test machines

Most Minnesota DWI arrests involve two different breath tests. And this confuses drivers. Insiders, like police, lawyers, and judges tend to be blind to this reality. So, what’s the problem?

What is the PBT?

The first breath test machine a driver encounters is a Preliminary Breath Test machine (or Portable Breath Test, “PBT”). The PBT is a screening test machine. A screening test is too inaccurate for use as evidence in a trial. But it’s accurate enough for use as a screening test for an arrest, to rule out alcohol. As with any breath test machine, a PBT is vulnerable to machine errors as well as human and environmental errors.

After a traffic stop, if the statutory preconditions exist, police may request that the driver blow into a PBT. If the driver then refuses, police can lawfully arrest the driver. And if the driver allows the search and blows 0.08 or more, police can lawfully arrest the driver.

Police use the PBT to support probable cause to arrest. But the prosecutor generally cannot use it in the criminal trial.

What’s an “Evidentiary” Breath Test machine?

Minnesota now uses a Datamaster DMT Breath Test machine as its evidentiary breath test machine. The state views it as accurate enough for use as evidence of breath alcohol concentration. But it has many problems that make it inaccurate and unreliable. We already saw some of them above.

They meant to do that!

Defective Minnesota version: The Minnesota DMT machine has both infrared and fuel cell technology, as an accuracy check. But when the two technologies consistently failed to match, what did the state government do? Fix it? No. They simply turned off the fuel cell technology in the machine! That was years ago. They haven’t bothered to fix it, or to offer a good excuse for failure to do so.

So now the DMT uses only infrared light technology, just like Minnesota government’s obsolete Intoxilyzer breath test machine did.

Driver confusion: “I already did a breath test!”

Driver confusion arises when a police officer asks a driver at the police station: “Will you take the breath test?”

Many say: “What? I already did, at the side of the road. You want another one?” (The PBT.) And sometimes this leads to the police officer choosing to label the driver as a “test refusal.”

You see, the normal DWI investigation includes a handheld, PBT breath test at the side of the road. And then comes a larger, tabletop, DMT breath machine, later on, at a police station. But the two different “breath tests” confuse most drivers.

Prevention

The laws are too complex. But on an individual level, it makes sense to learn about them ahead of time. Of course, avoiding driving near or above the arbitrary 0.08 alcohol concentration should be prevention — the best defense. But what is plan B? See my in-depth look at prevention:

Avoiding a DWI: Countermeasures.

For now, a few highlights:

• Never do field exercises, “Field Sobriety Tests,” like “Nine Step Walk & Turn,” or “HGN watch the pen.” Police cannot require them. They are fake “tests,” that never help the driver.
• Always ask to call a lawyer before consenting to a breath, blood or urine sample for chemical testing
• Always get an independent, Additional Test of your blood or urine soon after.

Cure

If it’s too late for prevention, you need a good DWI defense attorney for the cure. So, we look for causes of an inaccurate reading as well as police mistakes that hurt the driver. And when we find them, we can win the DWI case for our client. We don’t win every case. But no one wins unless they challenge the government’s cases.

DWI Attorney Thomas Gallagher

Thomas Gallagher teaches CLE classes to lawyers and judges on DWI law.

And Attorney Thomas Gallagher has 35 years of experience winning DWI cases in Minnesota.

Question? Call Attorney Thomas Gallagher, 612 333-1500

He helps clients remove alcohol-related incidents from their drivers license records. And this saves them money – more than attorney’s fees. For some clients with prior convictions, their priority is avoiding prison or jail. For example, a fourth in ten years is a felony DWI with presumptive prison time.

And DWI Attorney Thomas Gallagher helps them. Sobriety is a big help, but there is more to do, for a win.

More

DWI Frequently Asked Questions: Minnesota DUI Law

Guide to DUI Defense in Minnesota

Felony DWI Charges and Defense

Driving After Revocation Defense

About Defense Attorney Thomas Gallagher