Ed Brayton is a journalist, commentator and speaker. He is the co-founder and president of 
Here's a very interesting case from Florida, where an appeals court has upheld a lower court ruling that threw out evidence from a breathalyzer test in a drunk driving case because the manufacturer of the device refused to release the source code and allow defense experts to analyze the accuracy of the machines.
The results of breath tests in more than 100 local drunken-driving cases will not be allowed at trial, a judge announced Tuesday.The validity of those breathalyzer tests has been challenged for more than three years because of the Intoxilyzer 5000, a machine that uses a breath sample to measure a person's blood-alcohol content.
Manatee County Judge Doug Henderson ruled two years ago that any Intoxilyzer 5000 tests were inadmissible in trial, but prosecutors appealed. On Tuesday, Henderson told lawyers that his ruling had been affirmed by the Second District Court of Appeal and Circuit Court.
Breath analysis machines are notoriously inaccurate and this has been a problem for a very long time. Dr. David Hanson, a sociologist who has written on this issue for decades, writes:
Breath analyzers (Breathalyzer, Intoxilyzer, Alcosensor, Alcoscan and BAC Datamaster are common brand names) don't actually test blood alcohol concentration (BAC), which requires the analysis of a blood sample. Instead, they estimate BAC indirectly. Different types of machine use different techniqes and larger machines generally yield better estimates than do hand-held models. Therefore, some states don't permit data or "readings" from hand-held machines to be presented as evidence in court. South Dakota does not even permit evidence from any type or size breath tester but relies entirely on blood tests to ensure accuracy and protect the innocent.A major problem with some machines is that they not only identify the ethyl alcohol (or ethanol) found in alcohol beverages, but also other substances similar in molecular structure. Those machines identify any compound containing the methyl group structure. Over one hundred compounds can be found in the human breath at any one time and 70 to 80 percent of them contain methyl group structure and will be incorrectly detected as ethyl alcohol. Important is the fact that the more different ethyl group substances the machine detects, the higher will be the false BAC estimate.
The National Highway Traffic Safety Administration (NHTSA) has found that dieters and diabetics can have acetone levels hundreds and even thousand of times higher than that in others. Acetone is one of the many substances that can be falsely identified as ethyl alcohol by some breath machines.
One investigator has reported that alcohol-free subjects can generate BAC readings of about .05 after eating various types of bread products.
Substances in the environment can also lead to false BAC readings. For example, an alcohol-free subject was asked to apply a pint of contact cement to a piece of plywood and then to apply a gallon of oil-base paint to a wall. The total activity lasted about an hour. Twenty minutes later the subject was tested on an Intoxilyzer, which registered a BAC of .12 percent. This level is 50% higher than a BAC of .08, which constitutes legal intoxication in many states.
Similarly, a painter with a protective mask spray painted a room for 20 minutes. Although a blood test showed no alcohol, an Intoxilyzer falsely reported his BAC as .075.
Any number of other products found in the environment can cause erroneous BAC results. These include compounds found in lacquers, paint removers, celluloid, gasoline, and cleaning fluids.
Other common things that can cause false BAC levels are alcohol, blood or vomit in the subject's mouth, electrical interference from cell phones and police radios, tobacco smoke, dirt, and moisture.
Breath testers can be very sensitive to temperature and will give false reasings if not adjusted or recalibrated to account for ambient or surrounding air temperatures. The temperature of the subject is also very important. Each one degree of body temperature above normal will cause a substantial elevation (about 8%) in apparent BAC.
Many breath testing machines asume a 2,100-to-1 ratio in converting alcohol in the breath to estimates of alcohol in the blood. However, this ratio varies from 1,900 to 2,400 among people and also within a person over time. This variation will lead to false BAC readings.
Physical activity and hyperventilation can lower apparent BAC levels. One study found that the BAC readings of subjects decreased 11 to 14% after running up one flight of stairs and 22-25% after doing so twice. Another study found a 15% decrease in BAC readings after vigorous exercise or hyperventilaion.
Some breath analysis machinnes assume a hematocrit (cell volume of blood) of 47%. However, hematocrit values range from 42 to 52% in men and from 37 to 47% in women. A person with a lower hematocrit will have a falsely high BAC reading.
It's about time a judge took a stand on this issue.
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Comments
I read this blog every day there's a new post: www.duiblog.com
It deals with a lot of the issues involving what you posted above as well as unconstitutional measures being allowed by the courts. Hopefully something will be done about this soon!
Posted by: llDayo | January 21, 2009 10:15 AM
In the early 90s I was on a jury for a drunk-driving case (in North Carolina). The defense tried to introduce evidence that the breathalyzer used had a history of innacuracy, but was denied the chance by the judge. We were told point-blank, that legally if the machine said he was intoxicated then he was. No gray areas. No taking into account his behavior or condition at the time of his arrest. No criticism of the ridiculous "field test" he'd undergone was to be considered relevant.
None of us thought the man was drunk. But we had no choice (as it was explained to us) but to find him guilty. I was only 19 at the time and it made me disgusted with the justice system; a disgust I continue to feel today. Your post today reinforces my disappointment.
I recognize the serious problem of drunk-driving but things are stacked too heavily for the prosecution (at least they are in NC). Good for this judge!
Posted by: Savagemutt | January 21, 2009 10:17 AM
Savagemutt, given your age at the time, I will not cast aspersions on your decision to convict. But for others who find themselves in a similar jury situation, I would offer the possibility of jury nullification. It only takes one jurist to cause a mistrial, and a sufficiently impassioned jurist might even be able to sway the rest of the panel.
Posted by: BruceH | January 21, 2009 10:29 AM
We have a similar case going on in Arizona right now I believe--not sure if it's been resolved yet. It might even be the same company/device. The name sounds familiar but I'm not sure.
Posted by: Uncephalized | January 21, 2009 10:47 AM
These machine measure methyl- groups. So you mean if I have a beverage with a high concentration of 1,3,7 Trimethyl pyrine 2,6 dione*, it'll get a false positive? Crazy. - DJ
*also known as Caffeine, not generally considered an intoxicant.
Posted by: DingoJack | January 21, 2009 10:53 AM
BruceH,
While I'm aware of the concept of Jury Nullification now (I wasn't at the time, as you surmised), I'm still not certain I would have used it. I haven't worked out for myself any coherent view about jury nullification. I can certainly see times when it might be used, I worry about its potential for misuse.
If I'd known then what I know now I think I would've just asked to be excused from the Jury (as I did for a drug case some years later).
Maybe that's too wimpy, but then I'm a wimpy wishy-washy sort.
Posted by: Savagemutt | January 21, 2009 11:08 AM
DingoJack:"These machine measure methyl- groups. So you mean if I have a beverage with a high concentration of 1,3,7 Trimethyl pyrine 2,6 dione*, it'll get a false positive? Crazy. - DJ
*also known as Caffeine, not generally considered an intoxicant."
The compound in question must have a non-negligible vapor pressure. Drink all the coffee you want. The problem with ketosis (diabetes or diet induced) is well known.
Posted by: t_p_hamilton | January 21, 2009 11:09 AM
I think MADD's position on this would be "Better that a thousand innocent people are convicted, than one guilty person goes free".
Posted by: soboco | January 21, 2009 11:39 AM
t_p_hamilton posted "The compound in question must have a non-negligible vapor pressure. Drink all the coffee you want. [It doesn't have enough vapour pressure to register as a false positive]"
Never thought of that!
Still, you don't know how strong I like my coffee (Show the coffee grounds water in a sealed container, no closer than 1m away for a few seconds...) :D DJ
Posted by: DingoJack | January 21, 2009 11:40 AM
I think the unquestioned use of breathalyzers (and other drug tests) is another case of scientifically incompetent people deciding how things should be done.
Posted by: rnb | January 21, 2009 1:10 PM
Posted by: James Hanley | January 21, 2009 1:45 PM
The ablitiy to arrest people must not be infringed by any science arguments or excuses.
And it has to be easy to do in the field, with a great show of process, so that the subject will acquiess in his arrest..
Posted by: Kevin | January 21, 2009 2:52 PM
Kevin, I'm not sure I follow. Are you saying it doesn't matter whether or not the technology works, so long as we all pretend that it does? Are you by any chance a cop?
Posted by: Abby Normal | January 21, 2009 3:30 PM
Abby, I think I detect sarcasm in Kevin's statement, especially since he's using the language of constitutional amendments, which a real law-and-order type wouldn't want to do, since he'd be calling attention to the weakness in his argument.
But hey, Poe's Law.
Posted by: chancelikely | January 21, 2009 4:25 PM
If you ever arrested for DUI, demand a blood test.
Posted by: David C. Brayton | January 21, 2009 4:42 PM
I hope so Chancelikely. I think someone replaced my brain with a baked potato while I slept last night. My thoughts have been starchy with hint of sour cream all day. :(
Posted by: Abby Normal | January 21, 2009 4:48 PM
"If you ever arrested for DUI, demand a blood test."
Since I'm a diabetic, you betcha!
Posted by: rnb | January 21, 2009 4:55 PM
Here in Australia, we have used breathlysers for about 20 years. However, these are just used to establish probable cause and a proper blood test must be undertaken for a conviction to be recorded.
Posted by: Andrew | January 21, 2009 5:25 PM
"If you ever arrested for DUI, demand a blood test."
I will. But do they have to give me one? And could the possible delay in getting a blood draw done be enough to make a jury believe that I was drunk at the station when they did the breath test, but slipped under the legal line by the time I got to the hospital lab? Especially if the breath test was barely over the limit? (I'm assuming most small-town police don't have facilities to do a blood test onsite.)
Even if they don't accede to my demand, I would think that a strenuous demand for a blood test and a police denial of it would help lend some weight to the defense.
Posted by: BobApril | January 21, 2009 5:55 PM
BobApril: Here in NC, the blood test is considered conclusive if performed within an hour of the arrest, and is still the presumption (rebuttable) if longer. If you demand it, they have to provide it. Your mileage may vary in other jurisdictions.
It's about time the world started catching on to this racket.
Posted by: kehrsam | January 21, 2009 6:20 PM
Dodgy electronic machines in Florida. Well, colour me surprised!
Posted by: Hank | January 21, 2009 6:35 PM
Well, in the UK, readings from the small hand-held machines are simply used as an indication of a potential drunk driver, but aren't valid as evidence in court. If you fail a roadside test, you are taken to a police station, where another breath sample is taken by specially trained personnel, into a far larger and more accurate machine. In addition, it's standard procedure that, if there is any reason whatsoever to think that a breath sample may not give an accurate reading, a blood sample is taken, unless you have a very good reason for refusing to provide this, in which case a urine sample is taken instead. You also have the right to insist on a blood or urine sample being taken instead.
Posted by: Smidgy | January 21, 2009 8:13 PM
Huh. I've never heard about this issue before....
That's actually fairly disturbing.
Posted by: Azkyroth | January 21, 2009 11:20 PM
Finally some good news. As bad as the war on drugs has been to civil liberties and well logic and science the war on drunk driving has been much worse. This war gave us the great loop hole in the 4th amendment of dui checkpoints. The state the power usually strike that almost always to take a person license away and the "judge and jury" in this case is the DMV supervisor whom usually have no college degree.
Smidgy- The term more accurate machine really is meaningless when talking about breathalyzers as these machines are at best misapplied science but in reality pretty much pseudoscience. DUI blog has lot of resources about the problems with even the best cared for machine.
Posted by: Jim | January 22, 2009 12:34 AM
Jim - just to play devil's advocate for a second...
Are YOU going to be the one who explains 4th amendment rights and pseudoscience to the mother whose child was killed by a drunk driver?
Road fatalities have been decreasing over the last 10 - 20 years due to a combination of factors, greater awareness of the dangers of drunk driving (and the fear of being caught) is one of these factors. Here the number of road fatalities reached a low not seen since the Second World War, despite more vehicles and more kilometers been driven.
Besides the DMV (or the like) doesn't decide if you lose your license to drive, surely a magistrate (or the Imperial equivalent) makes that decision. -DJ
Posted by: DingoJack | January 22, 2009 1:25 AM
@DingoJack: There are a lot of reasons for road fatalities dropping, most of them completely unrelated to drunk driving.
Yes, I'd be the one to explain that to a mother whose child was killed by a drunk driver.
Would that mother be willing to tell the thousands of people falsely convicted of a crime their wrecked lives are justified as vengeance for her child? Well, the ones in MADD would, but I mean the ones that aren't.
MADD and their ilk have become less a crusade against drinking and driving and more a crusade against drinking or driving.
They've succeeded in putting a DUI charge on par with violent crimes or sex crimes for the social stigma involved.
Posted by: JThompson | January 22, 2009 4:31 AM
Back in the days when I got drunk I got a DWI and since I couldn't stand up the cop waived the "field test" and we went straight to the hoosegow. When I blew into the machine he said "You blew a .18, do you want to see it" (this was not said sarcastically, the officer was totally professional and courteous). I said , "I can't see that far". MADD people are just that, mad. A lot of those folks would benefit more from Al-Anon (Take what you like and leave the rest, including the GOD stuff) than they do from trying to unrepeal prohibition.
I'm not excusing drunk driving, but if it's such a danger why not just tax the shit out of alcohol or make it illegal (I'm not suggesting the latter would solve ANY problem)?
Posted by: democommie | January 22, 2009 7:54 AM
I was once on the jury in a DUI trial where the evidence was a breathalyzer test that was only marginally above the legal limit.
We let him off because no information was given to us about the margin of error involved in such tests (though the defense should have brought this issue up--and didn't).
Posted by: DBE | January 22, 2009 8:13 AM
JThomson - I can't say what happened to you, I can only relate my experience.
RBT (Random Breathe Test) Vehicles, are PART of the solution to reducing deaths and injuries on the road.
My legal advice (from a tame lawyer) is that breath tests are simply 'probable cause', only a blood test is admissible as evidence. These issues are deal with in court, not the road-side.
IF you don't think the breath test is accurate, tell your defense lawyer to fight it on the basis that such tests are an INDICATION of methyl- groups, NOT proof of intoxication.
RBTs DON'T pick up those whose drink at home, those who drink in private residences owned by others, or at bars or Public Houses and take taxis home, only those who are foolish enough to drink then drive.
Have fun, but DON'T imagine your right to drink supercedes others right to live. -DJ
Posted by: DingoJack | January 22, 2009 9:25 AM
DingoJack,
What about my right not to be arrested if I fail a breathalizer test because I'm a diabetic, when I have not been drinking?
Posted by: rnb | January 22, 2009 11:07 AM
Two words - blood & test. -DJ
Posted by: DingoJack | January 22, 2009 11:13 AM
DingoJack- [quote]Are YOU going to be the one who explains 4th amendment rights and pseudoscience to the mother whose child was killed by a drunk driver?[/quote]
Well since I am not clergy or a cop probably not. But that has no bearing what so ever. Torture might lead to information that saves lives also, do you support that too?
Never mind that their is not enough cops or money to insure that anyone with a high BAC is pulled over before leaving the parking spot. In your scenario there will almost certainly be probable cause to suspect that the person has a high BAC and a blood test can be ordered all but insuring conviction.
[quote]Road fatalities have been decreasing over the last 10 - 20 years due to a combination of factors, greater awareness of the dangers of drunk driving (and the fear of being caught) is one of these factors.[/quote]
Actually not really, the number of deaths due to a "drunk" driver has been basically the same for the last 15 to 20 years in the US. The first push by MADD before the went insane did have an impact but once they became a neo prohibitionist group the numbers leveled off to around 1500 a year. Please do not come back with using the NHTSA numbers as they are pure bullshit. The count in that number any fatality where even a passenger had a drink even if they where the victim car. They also add not one but two smudge factors to count for the unaccounted.
[quote]Besides the DMV (or the like) doesn't decide if you lose your license to drive, surely a magistrate (or the Imperial equivalent) makes that decision.[/quote]
Actually the DMV does in the US. Most if not all states also give you a whopping 10 days in order to even call for a hearing to keep your license. The burden of proof is on the accused and there is no rules of evidence.
Posted by: Jim | January 22, 2009 12:58 PM
Jim - did you not see the word 'HERE'?
In Australia the road fatalities have reached a low not seen since 1942-3. I hardly think it's due to improved infrastructure (Exhibit A The Pacific Highway), but probably due to (AMONSY OTHERS) 'Booxe Buses'.
Would I support torture? No. Since it has NEVER been proven to, even remotest sense, save lives. Making sure drink drivers don't get to plow into other motorists, cyclists or pedestrians DOES.
As to DMV having the power to remove licenses, I would challenge such a hearing as being unconstitutional. Only a court should hear such cases, as only a court is qualified to interpret to law. -DJ.
Posted by: DingoJack | January 22, 2009 1:16 PM
James Hanley wrote: "A wimpy wishy-washy savage mutt? Now you've just caused me some cognitive dissonance that won't dissipate for hours!"
I tried "Milquetoastmutt" but it was too hard to spell.
Posted by: Savagemutt | January 22, 2009 6:13 PM