Archive for December, 2004

Alcohol on the Breath: Evidence of DUI?

Saturday, December 11th, 2004

As any experienced criminal attorney knows, you will never see a DUI police report that does not say the arrestee had "an odor of alcohol on his breath" — usually further characterized as either a "moderate" or "strong" odor of alcohol. If the report does not mention an alcoholic breath, you can be sure the later breath test at the station came back clean — and the arrest has been "revised" from DUI alcohol to DUI drugs.

Criminal attorneys also know the reality of drunk driving investigations: after stopping a car late at night, the officer approaches the driver’s window predisposed to finding a drunk driver behind the wheel. It is a psychological fact that we tend to see what we expect to see. And the first thing the officer will be looking for to corroborate his expectations is an odor of alcohol. Once he smells alcohol, the arrest is a foregone conclusion; the field sobriety tests are mere formalities, the subjective "pass-fail" decision made by the already-convinced officer.

Of course, as I indicated in an earlier post, "The Suspect Had a Strong Odor of Alcohol on his Breath", alcohol actually has no odor. I have received queries after this post as to whether there are any scientific studies to back up my claim that breath alcohol odor is largely irrelevant yet disproportionately weighted as "evidence" of intoxication. Yes, there is such a study…

In 1999, the same scientists whose federally-contracted studies became the basis of the so-called "standardized" battery of field sobriety tests conducted another study on the effectiveness of alochol odor in detecting intoxication.These researchers used 20 experienced officers working with 14 subjects who were tested at blood-alcohol concentrations (BACs) ranging from zero to .13 percent. Over a four-hour period, the officers smelled the subject’s breath odor under optimal conditions, with the subjects hidden rom view.

The conclusions of the study: Odor strength estimates were unrelated to BAC levels. In fact, estimates of BAC levels failed to rise above random guesses. Further, officers were unable to recognize whether the alcohol beverage was beer, wine, bourbon or vodka. According to the scientists, these results demonstrate that even under the best of conditions, breath odor detection is unreliable. Moscowittz, Burns & Furgeson, "Police Officers’ Detection of Breath Odors from Alcohol Ingestion", 31(3) Accident Analysis and Prevention 175 (May 1999).


Rising Blood Alcohol Levels in DUI Cases

Thursday, December 9th, 2004

It is illegal to have a blood-alcohol concentration (BAC) of .08% or greater while driving a vehicle. It is not illegal to have a BAC of .08% or greater while blowing into a breathalyzer in a police station. In other words, just because a breath test shows a level of, say, .09%, it does not mean that the BAC when the suspect was driving an hour earlier was .09%.

So what was the breath alcohol level when driving?

Well, we’ll never know: There is no evidence of the BAC at the time of actual driving. However, we can be fairly sure that it wasn’t .09%, since the body is constantly either absorbing or eliminating alcohol and the BAC is therefore constantly rising or falling. If it was falling, then we can expect the BAC when driving was higher — .10% or more. But if it was rising…..

Let’s take a typical example. The subject — let’s call her "Janet" — finishes dinner by throwing down "one for the road", a 12-ounce can of beer containing .05% alcohol. She is stopped by an officer soon after leaving the restaurant, alcohol is smelled on her breath and she is given field sobriety tests. She does marginally well but, to be sure, the officer takes her into the police station for breath testing. About 45 minutes after drinking the alcohol, Janet breathes into the breathalyzer. The result: .09%. She is booked and his driver’s license confiscated.

It will take, on average, about one hour for the alcohol to be absorbed and reach peak levels of concentration in the blood, thereafter to be eliminated from the body. This is only an average; it can vary from 15 minutes to 2 hours; some invidividuals can reach peak concentration ten times faster than others. Dubowski, ""Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects", Journal on Studies of Alcohol, Supp. 10 (July 1985). This makes trying to estimate earlier BAC levels no better than a rough guess, and scientists have unifromly condemned the practice. See, for example, "Breath Alcohol Analysis: Uses, Methods and Some Forensic Problems", 21 Journal of Forensic Sciences 9.

Applying averages to Janet, though, we can expect the last drink to have had little if any effect on her blood-alcohol concentration while she was driving. By the time she is being tested at the station 45 minutes later, however, she is reaching peak concentration. In other words, Janet’s BAC has been rising. At about 120 pounds, we can estimate (read "guess") that the can of beer has increased her BAC by about .031%.

Translation: the breathalyzer reading of .09% at the station indicates a BAC while driving of only .06%. She is not guilty. But the "evidence" will convict her.

Just to make things worse….As I indicated, attempts to guess BACs when driving earlier than when tested have been condemned by scientists. This makes things tough for prosecutors. Solution? As I discussed in an earlier post, "Whatever Happened to the Presumption of Innocence?", most states today have passed laws — contrary to scientific truth — which presume that the BAC at the time of being tested is the same as at the time of driving!

In other words, unless the defendant can prove that his BAC was different than when tested, the jury will be instructed that they must find that it is the same. In effect, the defendant is presumed guilty. And since there is no evidence of the BAC when driving, there is no way for the defendant to rebut the presumption. These laws do, however, make getting convictions much easier.


Driving Under the Influence of….Paint?

Tuesday, December 7th, 2004

In my post "Why Breathalyzers Don’t Measure Alcohol", I mentioned one of the many reliability problems breath machines have: they will falsely report any of thousands of chemical compounds as "alcohol". Scientific studies have clearly proven this defect, referred to as "non-specificity".

In "Driving Under the Influence of…Gasoline?", I gave a practical example of one such compound. Is gasoline the only chemical product that has been proven to falsely register as alcohol on these machines? Far from it. See, for example, "The Response of the Intoxilyzer 4011AS to a Number of Possible Interfering Substances", 35(4) Journal of Forensic Sciences 797, where researchers found numerous common substances which were falsely reported by breathalyzers as alcohol — including methyl ethyl ketone, which is used in lacquers, paint removers, cements, adhesives, celluloid and cleaning fluids. Another compound, toluene, also caused false high readings and is commonly used in paints, lacquers, varnishes and glues. A third chemical is isopropanol, commonly known as rubbing alcohol. Fumes from these chemicals can be inhaled or absorbed through the skin.

In an interesting scientific study, researchers performed tests on a professional painter who was exposed to lacquer fumes under controlled conditions. In the first test, he sprayed paint in a room for 20 minutes, wearing a protective mask; his blood and breath were then tested. Although the blood test showed no presence of alcohol, a breath machine (Intoxilyzer 5000) indicated a reading of .075% blood-alcohol concentration –very close to the legal limit of .08%. "Lacquer Fumes and the Intoxilyzer", 12 Journal of Analytical Toxicology 168.

Yet another scientific study discovered that diethyl ether, found in some plastics and automotive products, can be inhaled and detected by breathalyzers as "alcohol". "Diethyl Ether Interference with Infrared Breath Analysis", 16 Journal of Analytical Toxicology (1992). The researchers concluded that "the possibility of interference with an alcohol reading by ether or by other substances may therefore render prosecution more difficult if not impossible."


Measuring the Invisible Breath Sample

Monday, December 6th, 2004

Many of my recent posts have been about the incaccuracy of breath machines used in DUI cases. But just how accurate do they have to be? What’s so special about measuring some alcohol?

Well, consider the amazingly tiny amount of alcohol these small machines are trying to measure, and the need for extreme precision becomes apparent — a precision which cannot be found in these portable, relatively inexpensive police-operated devices….

Let’s assume that a breathalyzer reading is .10%. This means that the suspect’s blood contained .10 grams of alcohol in 100 milliliters (cubic centimeters) of blood, or .001 grams per cubic centimeter of blood. A typical breath machine such as an Intoxilyzer 5000 captures 50 cubic centimeters of the suspect’s blood. Applying Henry’s Law, this means that the equivalent of 1/40th of a cubic centimeter of blood is represented by this breath sample. Since a cubic centimeter contains 20 drops, we can say that 1/40th of a cubic centimeter contains half a drop.

Assuming a .10% reading, then, the machine is attempting to measure five one-hundredths of one percent of a drop of alcohol — an amount invisible to the naked eye! To express this graphically, imagine a 55-gallon drum filled with water. This represents about the same capacity as 210 liters of breath — the volume used by law in determining breath-blood analysis. Then imagine taking an eyedropper with only one-tenth of a gram of alcohol in it, and adding this tiny amount into the drum. Now imagine trying to measure the amount of alcohol in the 55-gallon drum.

Now try it with a small, relatively cheap, portable machine maintained, calibrated and operated by police officers…..a machine that is not even warranted by its manufacturer to measure alcohol (see "Breathalyzers: Why Aren’t They Warranted to Measure Alcohol?"). The government calls this "proof beyond a reasonable doubt".


Breath Testing After “One for the Road”

Saturday, December 4th, 2004

It’s a common situation. You’re at a restaurant, it’s been a fine meal, you’ve paid the bill and it’s time to head home. You finish off the glass of wine and head for the car.

Bad move.

A few blocks from the restaurant, you’re stopped for speeding. The officer smells the wine still on your breath and asks you to step out of the car. A few minutes later and you’re on the way to the police station — and a breathalyzer. But you know that you and your wife each had only two glasses of wine from the bottle with dinner. The charts say that at your weight your blood-alcohol level should be around .05%, so you’re well under the .08% legal limit, right?

Wrong: the reading is .10%, your license is confiscated and you are booked for DUI.

What happened?

What happened was what the toxicologists call "absorptive stage analysis". In English, your breath sample was tested while your body was still absorbing the alcohol from the last drink. Any testing during this stage of absorption will result in falsely high blood-alcohol readings.

Explanation…..Your body will continue absorbing alcohol for roughly an hour after drinking, reaching peak blood-alcohol levels sometime before that point; the presence of food in the stomach can delay this for as much as 4 hours.During this one-hour period, the alcohol is passing from the stomach and intestine into the blood, but has not yet reached a stage of "equilibrium" — that is, uniform distribution of alcohol throughout the body.

In other words, some parts of the body will have higher levels of alcohol than others — in some cases, far higher.Since the alcohol is initially passing into the arteries, arterial blood will be much higher in alcohol content than will venous blood.

Where does the alcohol come from that is being measured by the breathalyzer?

That’s right: the arteries.

Arterial blood bathes the alveolar sacs of the lungs, and alcohol diffuses into the lung air — to be breathed out into the breathalyzer mouthpiece. As one of the most noted experts in the field of forensic toxicology has observed: "Breath is not a reliable means of estimating a subject’s BAC (blood alcohol concentration)…

There is a significant likelihood that a given subject will be in the absorptive state when tasted under field conditions. Because of large differences in arterial BAC and venous BAC during absorption, breath tests consistently overestimate the result that would be obtained from a blood test — by as much as 100% or more." Simpson, "Accuracy and Precision of Breath Alcohol Measurements for Subjects in the Absorptive State", 33(6) Clinical Chemistry" 753.

In other words, if you take a breath test within an hour or so after your last drink, you will have a false high reading — possibly twice as high as your true blood-alcohol level.