Breath Testing Blog Part 1 of 5

You Will NOT Blow This Topic

Breath testing for alcohol seems to be a mystery to the general public. For most people, breath testing devices are effectively magic boxes used to convict drunk drivers by showing a number above the so-called “legal limit."

It should be no surprise people’s understanding of breath testing usually is limited to two parts: 1) a person arrested for DWI/DUI blows breath into a tube connected to a machine; and 2) the machine produces a number to quantify a breath alcohol content or concentration (expressed as BrAC, as opposed to BAC, which is for blood). Everything between #1 and #2 probably is about as clear to people as how their mobile phones and computers work, which is to say not clear at all.

This blog series is intended to give the public an improved understanding of breath testing associated with driving while intoxicated arrests, primarily in Texas.

If you are worried the topic will go over your head because you aren’t a math whiz or scientist, don’t worry. You won’t need to be an expert on anything. Much like my blog on understanding and challenging blood tests , this talk is intended to simplify a relatively complex topic. Whenever a seemingly complicated term is used, I’ll endeavor to make it clear in its context.

By the time you finish reading the entire series, breath testing won’t be nearly as murky to you. My hope is you will have the healthy suspicion about breath testing I think it deserves. My guess is you will not want to blow into their device after reading this blog series.

You even may be influenced to absolutely avoid alcohol and drugs prior to driving. After all, if you reasonably suspect the evidence against you will include an inflated BrAC number, even truly being under the “limit” doesn’t protect you. Eventually, you may serve on a jury which hears breath test evidence and will think about what you learned.

Fine, I’ll Address It, Even Before Explaining Breath Testing: Should I Blow?

Before I go further, I will address the elephant in the room only because so many people ask. The predominant question I get about breath testing has nothing to do with understanding the topic. In fact, the question is indicative of the mysteriousness and fear of something people don’t understand at all. It’s all about what to do after getting arrested for DWI. “If I’m arrested for DWI, should I blow or not?” People still ask me about this more than anything else I do, even after 30 years. See another blog post about it for further information.

If you are asking that question, it presupposes you are planning on driving after drinking alcohol, which means you are planning on putting yourself at risk of arrest for DWI. That’s an unnecessarily risky plan. For anyone asking so they can plan what to do after getting arrested for DWI, my advice is to avoid getting arrested at all. No DWI arrest means you won’t need to go through one of the worst ordeals of your life. Simply do not drink alcohol at all before driving. Alternatively, you could ask a friend for a ride, get a rideshare or taxi, or drink where you’ll stay.

That’s not to condemn you for drinking and then driving when you are not intoxicated. The law doesn’t strictly prohibit driving after drinking alcohol, nor does intoxication occur with the slightest amount of alcohol consumption. However, you can reliably expect a cop to arrest you, should you be pulled over and have the odor of an alcoholic beverage on your breath. That is not to say they should base an arrest on so little, but they do.

Now that you’ve been advised and hopefully will avoid a future DWI arrest, I’ll address the actual question. However, I will explain, rather than simply giving a one-word answer, since I believe a simple “yes” or “no” to the question would be a disservice to you.

I have a professional preference, but there is no one correct or best answer to cover all circumstances. I am of the opinion the best idea usually is DO NOT BLOW. This opinion may not even matter, though, because you may never even get the chance to refuse a breath test, due to the fact the cop can decide not to offer you that option. 

In short, I would rather the state have less evidence than more evidence. Since the state has the burden of proof in a driving while intoxicated (DWI) case, the less evidence it has, the better the chances of a “not guilty” verdict.

If given a choice, I also would prefer evidence which allows me greater opportunities to argue for reasonable doubt. Blood testing has many more steps than breath testing to question and examine, and every step is an opportunity for error. Every such error could be the basis for a “not guilty” verdict.

Blowing may be helpful in some highly limited circumstances, but not most. Breath testing devices used in Texas can usually accurately detect the mere presence or absence of alcohol, even if the number is inaccurate.

So, the primary reason I’d suggest you blow into the state’s machine is when you have had no alcohol at all to drink, but that has extremely limited application. Relatively few people arrested for DWI blow a .00.

Even if that happens, you’ll probably have to defend a charge of being under the influence of drugs. After all, the cop already opined you are intoxicated, and a .00 breath test effectively eliminates alcohol as the intoxicant. To summarize, having no breath test is almost always better than having a breath test, but refusing a breath test does not mean cops won’t get evidence against you.

If you have had absolutely no alcohol to drink, a breath test MAY be good for you. However, clients I’ve defended have never been released by cops after a .00 BrAC result. Instead, cops just assume or pretend they know you are under the influence of a drug or drugs. Their next step is almost always to get a search warrant for blood.

As a rule, I think of the breath testing program as being unreliable and skewed to be unfair. It can and certainly does convict innocent people with inaccurate and unreliable application of science to criminal evidence in real-life cases. 

I think you should have a better understanding of breath testing to make sense of it, though. That brings us to the current blog series. Part 2 will cover the principles behind breath testing.

Important Notes

*THIS DISCUSSION IS NOT applicable to portable, hand-held devices used on roadside – This entire series is about the breath testing device whose result may be used as evidence of intoxication, NOT the roadside, handheld version.

My own observations as a DWI defense attorney reviewing evidence in many cases are Portable Breath Tests (PBTs, also known as Preliminary Alcohol Screening, or PAS devices) are extremely inaccurate and tend to skew higher than evidentiary breath test devices found in police stations and jails, as well as higher than blood results from a lab.

Rarely have I seen news published to address this observation, but a Corpus Christi, Texas, television station recently reported on such a situation. The news story on mentioned both the PBT result and a blood test result in an intoxication manslaughter case. The difference was roughly 50% higher with the PBT%. A “ preliminary test ” read 0.22 on a sample of breath. A blood draw from two hours later on the same person had a .15 result.

I acknowledge the importance of the difference in timing between samples. However, in the event you think the two hours caused the 50% difference of .07, you’d have to assume an alcohol elimination rate far in excess of the normal rate of .015-.020 per hour. Elimination phase is essentially when alcohol is metabolizing or excreting from the body, what most people would think of as the process of “sobering up” after being intoxicated. Two hours between the samples barely makes up half of that .07 difference, even if you make the ASSUMPTION the person was in the elimination phase the entire time.

*Breath testing is NOT necessary for prosecutions of Public Intoxication and underage drinking charges. Occasionally, it may be included with DUI (Driving Under the Influence of alcohol by someone under 21 years of age) and Minor in Consumption/Consumption of Alcohol by a Minor.