Breath-Alcohol Analysis: How Reliable Is It?
By Gerald D. Simpson, Ph.D.
In a 1983 law review article, Stephen G. Thompson observed the following:
“Modern criminal justice is premised upon the requirement that a criminal defendant be proved guilty beyond a reasonable doubt before punishment can be meted out. This standard of proof is severe; its severity is based upon a collective societal judgment that the risk of error be borne by the state. As fundamental and unquestionable as this principle may seem, it is frequently tested when the interests of society appear urgent, immediate, and identifiable. In these instances, society often creates policies and systems which threaten the presumption of innocence.”
Breath testing is a good example of the use of scientific evidence that routinely deprives suspects and defendants of the presumption of innocence and results in wrongful convictions as well as unwarranted guilty pleas.
The reason for this is that breath testing as now employed does not accurately reflect the true or actual value of alcohol concentration in the venous blood or even in the breath of a human subject.
SCIENTIFIC PROBLEMS
Current scientific research, published in respected peer-reviewed journals, now shows that results from breath alcohol analysis or breath testing are not sufficiently reliable for use in our courts. This represents a huge problem because breath testing has been used widely for this purpose for over 50 years and continues in widespread use on a daily basis.
What has now been demonstrated is that three important aspects of breath testing are faulty or even downright wrong:
- The very basis for breath testing in humans is the theory that ethyl alcohol (ethanol) in the blood is in equilibrium with the alveolar air in the lungs and that by measuring the concentration of ethanol in the end-expired air sampled by a breath machine, the amount of ethanol in the blood or breath can be reliably determined. Recent work by Michael Hlastala at the University of Washington Medical School in Seattle has shown that there is no such equilibrium and that breath testing therefore cannot work.
- Evidential breath testing has a very large margin of error, a minimum of +46%, meaning that for a given individual the breath test result can be anywhere from 0 to 46% higher than the actual amount of alcohol in the blood. This is the minimum amount of error that is indicated by the most recent scientific research. The actual amount could well be far greater.
- It has been recently shown that the “calibration” method used to ensure reliable performance of evidential breath machines does not work. The method used to “calibrate” these machines on a regular basis deals with only a fraction of the total error or uncertainty involved in a breath test result for a given individual; it simply ignores the major sources of error involved in results from evidential breath machines, e.g. error that occurs from assuming that the blood/breath ratio is 2100:1. Consequently, the actual amount of error in a breath test result for a given individual is unknown.
LEGAL PROBLEMS
Despite the fundamental scientific shortcomings of breath testing as used in criminal and civil cases, our courts continue to consider such evidence as an acceptable indicator of the inability to drive safely.
One issue that should be taken to the U.S. Supreme Court involves the destruction of evidence when breath testing is are given.
When a suspect is given a breath test, the breath sample is discarded, even though the technology to save the breath sample has been readily available for many years. This issue was taken to the U.S. Supreme Court in a California case called Trombetta many years ago (1984) and the court ruled that breath test samples need not be saved.
It is time to revisit this issue because research done in the 1990s makes it clear that breath testing is far less reliable than blood testing, and far less reliable than the Trombetta court was led to believe, yet it is blood samples that are retained by forensic laboratories and breath samples are discarded.
There are at least 100 volatile compounds (other than ethyl alcohol) that can cause false readings on a breath test device.
This is a compelling reason why the breath sample should be saved for reanalysis. A simple gas chromatography analysis can determine if any other compounds are contributing to, or are responsible for the entire reading. The prosecution must provide an unequivocal identification of ethyl alcohol and show that it is responsible for the entire reading produced by the breath test device. Without this, the evidence would appear to be insufficient for a reasonable juror to conclude guilt beyond a reasonable doubt.
Because a criminal charge is involved, regulation should be at least as strict as it is for medical or clinical laboratories for which 95% confidence limits are used to meet a standard of reasonable medical certainty.
Breath testing is actually a clinical chemistry analysis because alcohol concentration is being measured in a human body fluid (breath). Consequently, when used for legal purposes in criminal cases, regulations should require at least 95% confidence limits (some have argued that 99% confidence limits are appropriate to meet a standard of beyond a reasonable doubt).
Consider a political poll in which one candidate gets 49% of the vote and the other 51% of the vote, and the margin of error in the poll is +/- 4%. Since the result is within the margin of error, the race is too close to call. Confidence limits are part of how the margin of error is determined.
If one wants to be 95% certain that a subject’s blood alcohol concentration or breath alcohol concentration are not being over-stated by the breath machine result, an appropriate correction factor must be used.
For example, most statutes now criminalize driving with a BAC of 0.08%, and to be 95% certain that the 0.08% limit is in fact exceeded, a person would have to have a test result 40% greater than 0.08%, which is 0.112%. For 99% confidence limits the result must be 46% greater than 0.08%, or 0.117%.
At best, however, statutes and courts allow only +/- 0.01% for the margin of error in breath test results.
KNOW YOUR RIGHTS
Drivers need to know what their rights are in order to minimize the chances of wrongful arrest and conviction.
A driver has the right to politely refuse to answer any questions about drinking.
It is likely that the officer will persist in an attempt to get the driver to admit to alcohol consumption to make their case stronger. There is, however, little chance that a driver’s explanations will keep an arrest from happening, so it is better to remain silent about anything having to do with alcohol consumption.
A few things to keep in mind about field sobriety tests:
- If there are factors in play that compromise field sobriety test performance, such as poor balance or nystagmus due to injuries or prescription drugs the officer must be told about them in order to include them in his report.
- Hyperventilation prior to the breath test will significantly lower the test result.
- If the driver has had exposure to paints or solvents or is diabetic or has asthma, the officer must be asked to include these in his report as well.
- Refusal of a blood or breath test can be helpful in some jurisdictions and harmful in others for avoiding conviction at trial, but usually results in suspension of the suspect’s driver’s license.
CONCLUSIONS
The current status of breath testing is, as it has been for some 50 years, about the same as the status of DNA Fingerprinting was when if first began to be used in our courts. Forensic scientists adopted this methodology and began presenting it in courts as powerful evidence to identify suspects who left their DNA at the crime scene. At this time, like breath testing now, there was virtually no oversight or outside regulation of DNA Laboratories. Like breath testing, outlandish claims of accuracy and probability of a match were commonplace by those in the forensic science community, even under oath.
As time passed, very capable and informed defense attorneys were able to raise enough doubt about the claims that were being made that evaluation of the method by the National Academy of Sciences (NAS) was initiated. As a result, most of the scientifically unacceptable aspects of the procedures and methods used by DNA Laboratories were corrected, based on the recommendations of NAS committee members.
This is precisely what must be done with breath testing.
NAS consists of members of the main-stream scientific community, not forensic scientists. Indeed, forensic science is not one of the disciplines even represented in the National Academy of Sciences. NAS must be enlisted to evaluate the scientific merit of breath testing methods and procedures. If this is not done, the 50 year history indicates that neither the forensic science community nor our courts will solve the problem.
An immediate fix for the problems with breath testing is to inform jurors and judges that there are large unknown uncertainties in breath test results, and this must be factored into decisions of innocence or guilt of drunk driving. Long term solutions await development of direct, non-invasive blood alcohol tests.
Breath testing is now and will always be too unreliable to use for legal purposes, and when evaluated by NAS, this will eventually be shown to be true.
This information is excerpted from the forth-coming book: CSI/Forensic Fraud Cover-up by John Kelly who can be reached at: kjohn39679@aol.com.
This article has been adapted for use in this blog. You can read the full, unabridged article here: Breath Alcohol Analysis.
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One “expert” claims that breath alcohol testing is bogus and you are willing to throw out over 75 years of research, analysis and testing? You want to ignore Borkenstein’s research? Harger’s? Forrester’s? Gullberg’s? NHTSA’s? Every State forensic lab that must approve these units before they are used? You want to be taken seriously and yet you use Hlastala? Why isn’t he filing a federal class action lawsuit against each breath alcohol manufacturer? Against NHTSA (after all it is NHTSA that approves every breath alcohol testing unit for evidential use)? If you can scientifically validate your “conclusions” why aren’t you taking legal action on a national level? Here’s why: because breath alcohol testing works. It is accurate. It is precise. It is valid. If you wish to be taken seriously, how about “showing your work”? Stop your whining.
Bob,
Don’t you find it Ironic that with regards to speeding the NMA says all they want is to have scientifically set speed limits and they want to follow the 70 years of traffic engineering science that says we should post the 85th percentile speed for the greatest safety benefit. Then switch channels and go to the NMAs blog on drunk driving and all they want to do here is ignore the past 75 years of science and let all the drunks roam free on the highway. NMA asserts that they were formed to protect the rights of American Drivers. If you join and you get a ticket, go to trial and get found guilty, they will pay your fine. How does that program, of promoting careless and neglegent behavior in NMA members, protect my rights as an American driver? The NMA is for anything that relieves the drivers of responsibility for thier choices and thier actions, they have no desire to make our highways any safer, and all they really want is freedom from financial retributions attached to poor driving choices.
My husband was arrested for DUI recently. We are set for court soon. The officer did not mark anything down during the fiel sobriety test. When it was time for the breathalyzer he did not inform my husband to take out his dentures, even though he had asked the question on the form and marked that he did have them. He told my husband it would be fine if he could make a seal around the machine. His test showed a BAC of .12. When we got home I calculated the amount it should have been on a BAC calculator through some website. It showed that he should have had a .02 reading. We plan on fighting this with a defense of mouth alcohol as he really was not incompasitated. What I want to know is, can we sue the police for neglagance? This is costing us over 5,000 in legal fees along with the severe emotional strain. If the test had been done properly this would not have happened and I do not feel we should have to bear this cost. I am not wanting a huge settlement but in a family of six (4kids 10 and under) this is a huge finacial burden; but at the same time, I do not see trusting a public defendent with this. We were pulled over for a headlight being out and there were no irregular driving or any video of the arrest. Also the cop left me in the car (and I had atleast three or four more drinks than my husband, which my husband told the officer because he was conserned for me.) and told me to sit there for an hour or two and come pick him up at the station. Obviously he didn’t think I was over the limit. I realize the officer did not know what he was doing and was trying to be nice, but the fact is his neglagence has costed us a lot.
Diane spero writes(here in wst palm beach, fl they droppd a bunch of dui’s because the breathalyzer was not maintained properly. it is not a good indicater of blood alcohol. also cops do not know to adminster it properly.
It is a good thing when checks and balances work. If the Breathalyzer wasn’t maintained properly then any DUI’s based on the results should have to be tried without the results as evidence. I disagree and Believe when properly used it can be a good indicator of BAC and if someone is too intoxicated to drive an automobile. I disagree with the lower of stautory BAC levels to .08 though. I am sure that you meant only the cops in Wst Palm Beach(since that is who you are familiar with) When you said “also cops do not know to adminster it properly” Because a blanket statement to include all cops would mean you are aware of the training recieved nationwide by police officers, and could point out where there are deficiencies in that training for each geographical area of employment for those police officers.
I am not a lawyer but it seems insteed of fighting city hall to admit there is a flaw it there machine, say the breatalyzer 2000, that maybe a group of wrongfully charged individules who have had there lifes ruined. should sue the manufacture of the machine in a class action suit. as the manufacture it’s there 3rd party involvement that gives the false information leading to your pain and suffering and the finacial expence of so many not to mention the loss work, time in jail, impounded vehicle to so many while the manufacture profits from the knowingly false reading there product suplies.
mary i would request counsel , if you don’t have any. have them contact your dr. the dr can provide information regarding your condition and treatment. this should be investigated especially if they knew of your meds.
please fewe to email at preventionconnection@comcast.net i haven’t got my license back due to the inablity to do car breathalyzer due to breathing problem.
first lung dr didn’t not help me, going to another soon.
keep fighting i have been and will continue too.
diane
I amon probation for a DWI in New york State.For the second time I have tested possitive at probation .03.I have not been drinking I have sever asthma and alergies.I was arrested Monday and may be sent to jail for 6 months.The officers that had to take me in even suggesed that it is my medication.The probation officer says no and I must go to jail or in house rehab.I work 2 jobs and would become homeless when I got out.With all the people looking for jobs today I am sure mine would not be sae for 6 months.What can I do?
Draw blood!
i have an indented chest bone. i don’t have good breathing capacity. i got a refusel because i was physically unable to do it. was not offered the option of a blood draw.
here in wst palm beach, fl they droppd a bunch of dui’s because the breathalyzer was not maintained properly. it is not a good indicater of blood alcohol. also cops do not know to adminster it properly.
the one they want to put on my car, i could not do. have dr letter they want to try to have it so i can do it.
foods can trigger false readings on breathalyzers, perfumes, etc.
the one they put in cars is dangerous, if you don’t breathe fast enough when driving the car shuts off.
i would advise to have a lawyer who has sucess with dui, and one tells you to plead.
if i had the lawyer i have now this case would have been thrown out. there are issues than dui in my case.
madd has gone to far, its time for people to stand up for reasonable dui laws.
the cops, mad, dmv, insurance company’a are all in it together.
i have done 8 months of a dmv supervision program, for a license i don’t have.
someone has to take me 25 miles each way.
i have had many screw ups.
i will keep working till i get results.
i have letters verifying my recovery status, as letter from my therapist regarding my asperger’s syndrome
and how it effects me.
diane
I was caught for drink driving and was made to do a breath test. The 1st test shown mouth alcohol-result invalid, as I had sprayed a breath spray many times. I was told to gargle my mouth with water and retook the breath test again. The result shown 41 microgrammes of alcohol in 100 millilitres of breath, which exceed the prescribed limit of 35 microgrammes of alcohol in 100 millilitres of breath. I feel that the breath test is not accurate. Can anyone advise whether it does affect the reading of the test result? as I will be charged in court soon and if this could be considered a strong case I would like to engage a lawyer to appeal my case.
You need to keep in mind as well that part of the evidence or testimony will be the officers observations, which is now usually video and audio recorded not only during the soip but also prior to the stop to show how the person was driving. In Texas, and in most other places too, you can still be convicted of DWI even if your alcohol level is below the legal limit on a BAC or blood test. It will depend on the impairment at the time the person was operating the motorvehicle. And Ms. Diane, they should have given you the chance for a blood test or you could request it. Most in custody interviews are now videotaped and if the police had refused to let you take a blood test in lieu of the breath test, then they would have to explain why in court, especially after you had explained to them your difficulty in breathing. And for a refusal, here, DPS will automatically suspend your license.
i have a breathing problem. i was not able to do a breathalzer. i was given a refusal.
i am guilty because i pgysically can’t do it. i was nor offered a blood or urine test.
my police report says i did puff not blew,that is all i can do.
i could not do the car breathalyzer they want to install. i am going to a dr. can get a letter stating the fact i have very little lung function.
I recently conducted testing on the Intoxilyzer 5000. 9 stand shots of whiskey were given to 10 subjects. 10 different Intoxlizers were used. Breath and blood test taken. In every test the Intoxilzer was wrong! Yes wrong. Every breath test was between 7 and 22% less then the actual blood test results. If the 5000 was such a bad unit doesn’t one think that it still wouldn’t be around after 25 years?
Bob,
I would advise against the denile of a Brathalizer or FST’s for it automatically is a admission to guilt. If you are infact drunk i would refuse it though b/c is helps in your sentencing.
In my experience (5 years in ems, 15 in law enforcement)most people that are driving under the influence are no habitual offenders, they are the “reasonable drinkers” who have not drunk enough to be falling down obvious drunk, they have just had enough that it causes their reaction time to be just a little slower, or their ability to reason is off or their depth perception is effected all more than they realize. They don’t drive drunk intentionally they don’t know they are impaired, that is the real danger. So just don’t drink anything then drive. It is easy to either say no to a drink or to make other plans on how to get home.
Except that you are confusing drinking – a very common practice, even among reasonable adults – and drunkenness. I am utterly opposed to impaired driving. At the same time, not all drinking leads to impaired driving, especially with the ever diminishing level at which we declare that the person is drunk. Lowering allowed BAC levels expands the population of “criminals” but does nothing to identify the problem drivers, much less do anything about them.
Bob, why not just not drink and drive and then you don;t have to worry about killing yourself or someone else, going to jail, breath tests, field tests, pbts, jail, cops blood tests, evidence, fines, lawyers or anything else.\\DUH
In Montana, the state supreme court has said that if the only evidence of drunk driving the cops have is from a breath test, then the cops have no case because of the unreliability of such machines.
Just another reason to always refuse to do the roadside sobriety tests.