All devices, including breathalyzers, are inaccurate from time to time. That’s especially true if the device has many new bells and whistles, but the underlying technology is unchanged. A flip phone with a new battery is still a flip phone. Similarly, the modern breathalyzer is a souped-up Drunk-O-Meter, a device that was invented in 1927. Its inventor, W.D. McNally, originally marketed it to housewives who wanted to know if their husbands had been drinking.
This post examines some common breathalyzer inaccuracies. These inaccuracies loom very large in .08, .09, and other borderline BA cases. Breathalyzer manufacturers acknowledge that these devices can be inaccurate. Most breathalyzers have a margin of error of .001 BAC. A Marietta criminal defense lawyer expands these inaccuracies to create a reasonable doubt as to the breathalyzer’s reliability.
Probable Cause to Demand a Sample
Before we discuss scientific issues, we should examine legal issues. If police officers lacked probable cause to demand a sample, the sample is inadmissible in court.
Probable cause is a vague legal standard that’s somewhere between reasonable suspicion, the standard of proof for law enforcement contacts, and beyond a reasonable doubt, the standard of proof at criminal trials.
Physical symptoms, such as slurred speech, usually only prove consumption. The same thing is true for “I only had one beer” and other admissions. Generally, probable cause is poor performance on the field sobriety tests, which are:
- Horizontal Gaze Nystagmus: Police officers typically lead with the DUI eye test, because it seems like a safety test, as opposed to a field sobriety test. If the subject’s pupils move involuntarily during this follow-my-finger test, the subject probably has nystagmus, an eye condition that alcohol intoxication can cause.
- Heel to Toe Walk: The HTW is a divided attention test that measures physical dexterity and mental acuity. Scientifically, intoxicated people cannot think and act at the same time. Therefore, they cannot successfully complete this test.
- One Leg Stand: The same analysis applies to the one leg stand test. Specific intoxication clues include failure to follow directions, such as elevating the wrong leg or elevating it at the wrong angle, and physical impairments, such as swaying or using arms for balance.
These test results usually establish probable cause, but they usually do not constitute proof beyond any reasonable doubt. But that’s the subject of another blog.
Scientific Accuracy Issues
Georgia has an older DUI law which relies exclusively on “alcohol concentration,” a phrase that normally means blood alcohol level. A breathalyzer, like the Drunk-O-Meter that preceded it, uses breath alcohol level to estimate blood alcohol content. That extra step creates issues, such as:
- Unabsorbed Alcohol: The digestive process is usually over the lips and past the gums, watch out stomach, here it comes. But the liver filters alcohol before it goes into the stomach and thence the bloodstream. So, if the subject had been drinking within the past hour, that alcohol is still in the kidney or stomach, and his/her breath alcohol level artificially raises the BAC estimate.
- Temperature Variation: All the bells and whistles on the breathalyzer make it a very sensitive device. Small temperature variations, either air temperature or body temperature, skew the BAC estimate.
- Acetone Levels: Diabetics, smokers, and a few other individuals have high ketone levels in their bodies. Most breathalyzers register ketone as ethanol.
- Mouth Alcohol: If the defendant burps, belches, or vomits prior to the breathalyzer test, alcohol particles in the stomach rush into the mouth. Once again, the BAC estimate is artificially high. To solve this problem, Georgia law requires a fifteen-minute observation period. But courts don’t strictly enforce this rule, so there’s no telling what happened prior to the test.
We haven’t even mentioned calibration, which may be the biggest technical issue. Advanced breathalyzers require advanced maintenance. Usually, a breathalyzer tech must calibrate these gadgets.
In April 2023, a Massachusetts judge threw out 27,000 breathalyzer test results, partially because the devices weren’t properly calibrated. More disturbingly, authorities knew about the problem and did nothing to correct it.
Legal Accuracy Issues
The breathalyzer’s biggest flaw may be a legal issue. Prosecutors normally rely on breathalyzer technicians to authenticate the results, so they can be used in court. Usually, breathalyzer techs know a lot about the basic operational mechanism, which involves a fuel cell and a photochemical reaction.
However, many techs, especially new techs, don’t know much about obscure operational details, such as the difference between preliminary alcohol screening (PAS) tests and evidential breath tests (EBTs), the ideal partition ratio relative to sample size, and the role potassium dichromate plays in breath sample analysis.
If breathalyzer techs fumble questions in this area, they appear incompetent at best and biased at worst.
To draw a sharp contrast, a Marietta criminal defense lawyer often partners with a degreed chemist whose qualifications far exceed breathalyzer tech qualifications.
To Blow or Not to Blow
Given all this information, we now address a burning question on many people’s minds. Is it better to provide a sample or refuse to blow?
Subjects should avoid tricks at all costs. Never try to “fool” the breathalyzer by sucking on a penny or breathing shallowly. These tricks do nothing except prove the defendant has something to hide.
Many Marietta criminal defense lawyers believe DUI defendants should agree to provide samples. They reason that, if you’re stuck in a hole, the first thing to do is stop digging. The penalties for breathalyzer refusal are significant in Georgia. Therefore, from their perspective, refusal simply makes a bad situation worse.
We understand that perspective, but we disagree with it. The chemical test conviction rate is about twice as high as the refusal conviction rate. In other words, blowing into a breathalyzer gives the state it needs to convict you. The fallout of a refusal is severe, but it’s not nearly as bad as a DUI conviction.
Breathalyzers are usually inaccurate. For a free consultation with an experienced Marietta criminal defense attorney, contact The Phillips Law Firm, LLC. We routinely handle matters in Cobb County and nearby jurisdictions.
