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DUI, Field Sobriety Tests and “Circadian Rhythm”

Most drunk driving arrests take place at night, often after midnight. One reason for this is that many police officers engage in "cherry picking" — that is, the illegal practice of staking out bars and restaurants from about 10:00am to "closing time", pulling cars over on some pretext as patrons leave and drive away. It is during this period of time that the individual’s circadian rhythm is taking effect. The circadian rhythm is that 24-hour biological alarm clock in each of our bodies, most noticeable when we experience "jet lag".

Researchers have found that individuals will perform more poorly in tests during the low point of the circadian rhythm — that is, during the hours after midnight and into the early morning. It is just such tests — called "field sobriety tests" — that officers use to determine whether a driver is intoxicated or not. Specifically, British physicians and psychiatrists reported that "the same blood alcohol level is associated with a significantly greater impairment of different aspects of psychological funtioning when achieved in the morning." "Circadian Variation in Effects of Ethanol in Man", 18 (Supp. 1) Pharmacology, Biochemistry and Behavior 555. The researchers concluded that "the differences we have found…must be attributable to circadian change and susceptibility of the body to its effect."

Why Breathalyzers Don’t Measure Alcohol

That’s right: Breathalyzers don’t actually measure alcohol. What they actually detect and measure is any chemical compund that contains the methyl group in its molecular structure. There are thousands of such compounds — including quite a few which can be found on the human breath. And this machine that determines a person’s guilt or innocence will "see" all of those chemicals as alcohol — and report a falsely high "blood-alcohol" concentration (BAC).

Most breath machines used in DUI cases by law enforcement today employ a technology called "infrared spectroscopy". The DUI suspect breathes through a tube connected to the machine and a breath sample is captured in a small "sample chamber" inside the machine. Then beams of infrared energy are shot through the captured breath sample. If there are any compounds containing the methyl group, they will absorb some of this energy; the more of the chemical compound in the breath sample, the more energy is absorbed. The more energy that is absorbed, the less infrared energy that reaches sensors at the other end of the sample chamber. And the less energy that is detected by the sensors, the higher the "blood-alcohol" reading.

Problem: the machine is designed to simply assume that the chemical compound absorbing the energy is alcohol. If a person has any of these other compounds on his breath, called "interferents" by the engineers, he will get a falsely high BAC test result. And if there are two or three such compounds on his breath, the machine will read a cumulative result: it will add them up and falsely report the total as the blood-alcohol level.

So what kinds of compounds may be on a person’s breath that can cause false BAC readings in a DUI case? In one study of eight men, 69 different compounds containing the methyl group were discovered. "Trace Composition of Human Respiratory Gas", 30 Archives of Environmental Health 290. In another study invoviing 28 subjects, researchers found that teh "combined expired air comprises at least 102 various organic compounds of endogenous and exogenous origin". "Characterization of Human Expired Air", 15 Journal of Chromatographic Sciences 240. And Camnadian scientists have discovered over 200 such compounds. "The Diagnostic Potential of Breath Analysis", 21(1) Clinical Chemistry 5.

What are these compounds? Are there any on my breath?

Well, for starters, diabetics with low blood sugar can have high levels of acetone — which is "seen" as alcohol by Breathalyzers. And scientific studies have found that people on diets can have reduced blood-sugar levels, causing acetone hundreds of times higher than found in normal individuals. Frank and Flores, "The Likelihood of Acetone Interference in Breath Alcohol Measurements", 3 Alcohol, Drugs and Driving 1. And there are many other so-called "interferents". See, for example, "Excretion of Low-Molecular Weight Volatile Substances in Human Breath: Focus on Endogenous Ethanol", 9 Journal of Analytical Toxicology 246.

If you are a smoker, your Breathalyzer result is likely to be higher than expected. The compound acetaldehyde — reported by the Breathalyzer as "alcohol" — is produced in the human body as a by-product in metabolizing consumed alcohol, and eventually passes into the lungs and breath. Researchers have discovered that levels of acetaldehyde in the lungs can be 30 times higher in smokers than in non-smokers. Result: higher BAC readings on the machine.

And then there are the industrial compounds: paint, glue, gasoline, thinners, and other compounds contain the methyl group. No, you don’t have to drink the stuff: simply absorbing it through your skin or inhaling the fumes can result in significant levels of the chemical in your body for hours or even days, depending upon the "half-life" of the compound. So if you’ve painted a room or siphoned some gasoline in the last day or two, don’t breath into a Breathalyzer.

Some law enforcement officials say that this is not a problem, claiming that levels of the compound would have to be at toxic levels to raise a breath test result to .08% or higher. These officials are displaying their ignorance of the science involved — specifically, of the partition ratio. This is the ratio of the compound found in the breath to that found in the blood. With ethanol, the ratio is 2100-to-1, which means that, on average, there will be 2100 units of alcohol in the blood for every unit found in the breath.

These officials are using this ratio for all compounds, but every compound has its own ratio. Toluene (found in paint, glue, thinners, cleaning solvents. etc.), for example, has a partition ratio of only 7-to-1; a far greater amount of toluene in the blood will pass into the breath, and so a much smaller amount in the body will have a far greater impact on the breath machine.

Convicting the “Average” DUI Suspect

One of the greatest sources of error in breath-alcohol testing is the consistently recurring fallacy that the individual tested is perfectly average in certain critical physiological traits. Put another way, obtaining an accurate blood-alcohol reading in a DUI case is completely dependent on the validity of a number of assumptions. Unfortunately for the person being tested, these assumptions are usually incorrect: The person tested is rarely “average” in even one of these critical characteristics, let alone in all of them.

For example, all breath testing devices depend on the assumption that the ratio between alcohol in the exhaled breath and alcohol in the blood is 1 to 2100. In fact, the machine is designed to produce a reading based on that assumption; the accuracy of the reading is directly tied to the accuracy of the presumption. Yet, the actual ratio in any given individual can vary from less than 1:1300 to more than 1:3000. So a DUI suspect with a true blood-alcohol level of .08 but a breath-to-blood ratio of, say, 1:1700 would have a .10 reading on an “accurate” breath testing instrument.

Put simply, these machines do not test individuals. Rather, they test the same “average suspect” over and over again, but using the individual subject’s breath.

Another example of the assumption of “averageness” can be found in urinalysis. When a DUI suspect’s urine is analyzed for blood-alcohol, a presumption exists that there are 1.3 parts of alcohol in the bladder’s urine for every 1 part of alcohol in the blood. This 1:1.3 ratio is as fallacious as the 1:2100 ratio’that is, it is based entirely on the ratio found in the average person. In fact, however, the actual ratio found in any given individual can vary greatly. And as the ratio is in error, so will be the final blood-alcohol reading.

Another example of this constant reliance on averages shows itself when the prosecutor in a DUI trial offers evidence of so-called “retrograde extrapolation”, or guessing backwards. The blood-alcohol level at the time of testing is not relevant to the charge, of course, and so the state will offer evidence to show what the level was when the defendant was driving. This is commonly done by “extrapolating” backward’that is, computing the earlier blood-alcohol level by estimating how much alcohol had been eliminated or “burned off” in the period between driving and testing. But this requires two assumptions: The blood-alcohol level was declining and the rate of elimination is known. This second assumption involves the further assumption that the “burn-off” rate was .015 percent per hour (sometimes the assumed rate is .02 percent). How does the prosecution know that the defendant was eliminating (assuming he was eliminating rather than absorbing) at that rate and not at .005 percent or .3 percent? Quite simply, the prosecution does not know: It merely assumes that the defendant eliminates at the average rate. And, of course, error in such an assumption translates into error in the extrapolation.

This ever-present “average person” in the DUI arena is not limited to chemical analysis. We even find him with the arresting officer in the field. When the officer administers the “nystagmus'’ test (“follow my finger with your eyes”) as part of the battery of field sobriety tests, he operates on the assumption that the suspect is “Mr. Average.” The officer has been trained to “read” at what angle the suspect’s eyes begin jerking. If it begins before 45 degrees, the suspect fails. And where does the magic figure of 45 come from? The average person.

Don Nichols, a pioneer among DUI defense attorneys, would point out to juries that his client is female, Chinese and deceased’despite obvious evidence to the contrary. He then explains that statistically there are more women than men in the world, more Chinese than any other nationality and more dead human beings than living ones. Statistically, then, the average person is female, Chinese and deceased’and so, according to the prosecution, must be his client. He also asks the jury how many of them have 2.3 children’the average in the United States.

So why does the state presume facts that are clearly untrue? Simple. It is convenient: it makes prosecution and conviction much easier.

Breathalyzers: Why Aren’t They Warranted to Measure Alcohol?

If you are facing drunk driving charges, you will have taken (unless you refused) a chemical test for blood alcohol concentration (BAC). In the great majority of cases, the test will be done with a breath machine. When you go to court, you will find that you have been charged with not just one, but with two crimes.

The first is the so-called "per se" offense: driving while having a BAC of .08% or greater. No one cares whether you were intoxicated or not. All of the evidence could prove that without question you were sober: the crime is your chemical composition, not your condition. And what is the sole source of evidence upon which you will be either convicted or acquitted? A machine.

The second charge you are facing is "driving under the influence of alcohol" ("DUI"), or in some states, "driving while intoxicated" ("DWI") or "operating under the influence" ("OUI"). They are basically the same thing. In each case, however, the prosecution can prove you were under the influence of alcohol by offering the results of the same breath test into evidence — and the jury will be instructed that the defendant is rebuttably presumed to be guilty unless he can prove otherwise.

That’s right: a presumption of guilt. Based upon what? Again, a machine. So it all comes down to a machine. Your innocence or guilt depends largely if not entirely upon what a machine says. Maybe we should take a closer look at this "breath machine"….

Sometimes generically referred to as "Breathalyzers" after the original Breathalyzer 900, today there are a number of makes and models manufactured by different companies. For many years, the most popular of these has been the "Intoxilyer 5000", manufactured by CMI, Inc. How reliable is this machine at measuring alcohol in a person’s blood by measuring his breath? How accurate?

Well, what do the manufacturers think? How confidant are they that these devices are reliable enough to send a man to jail? Let’s take a look at their manufacturer’s warranty. The following is from their manual’s "Statement of Warranty":

"CMI, Inc., a subsidiary of MPD, Inc., warrants that each new product will be free from defects in material and workmanship, under normal use and service, for a period of one year from the date of delivery to the first user-purchaser…."

One year? These things are warranted for only one year? Model 5000s are commonly found in service at law enforcement agencies for ten years or more. What if there’s a problem with the machine requiring repair by the manufacturer?

"Repaired components are warranted for a period of 90 days from the date of repair."

90 days? The toaster in my kitchen has a better warranty. But the "warranty" continues:

"There are no other warranties expressed or implied, including but not limited to, any implied warranties of merchantibility or fitness for a particular purpose…."

What? CMI, Inc., says this machine is not warranted for any "particular purpose" — which, for the Intoxilyzer 5000, is measuring alcohol on the breath. So they don’t guarantee that it will measure breath alcohol? And this, the law says, is "proof beyond a reasonable doubt"?

Ok, let’s take a look at another of these machines which determine guilt or innocence: the BAC DataMaster, manufactured by National Patent Analytical Sytems, Inc. Their warranty, at least, is for two years –but with that same refusal to guarantee that the thing measures breath alcohol:

"There are no other warranties expressed or implied including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose."

And, as with CMI, Inc., there is the added warning that "In no event shall National Patent Analytical Systems be liable for any loss of profit or any indirect or consequential damages arising out of any such defect in material or workmanship". In other words, if you end up going to jail because of defects in our machines, you can’t sue us.

The simple fact is that, for perhaps the first time in our history, we are convicting people of crimes — beyond a resonable doubt — based entirely upon what a machine says. Are we that sure of their accuracy? Are the manufacturers?

Whatever Happened to the Presumption of Innocence?

In most countries of the world, an accusation by the State forces the accused to prove himself innocent. In America, however, the presumption of innocence has always been a fundamental part of our rights as a free people. This basic protection against the power of the government has been recognized as flowing from the 5th, 6th and 14th Amendments to our Constitution. As the United States Supreme Court has said, "The principle that there is a presumption of innocence in favor of the accused is the undoubted law, axiomatic and elementary, and its enforcement lies at the foundation of the administration of our criminal law." Coffin v. U.S., 156 U.S. 432 (1895).

So what happened to this presumption of innocence in a drunk driving case? Is this yet another example of "the DUI exception to the Constitution"? Let’s take a look at how our DUI laws have slowly eroded this fundamental right….

Let’s assume you have been arrested for drunk driving, and a Breathalyzer gave a reading of .09% blood-alcohol concentration (BAC). You will probably be charged with two crimes: (1) driving under the influence of alcohol, and (2) driving with over .08% BAC. Let’s look at the .08% charge first.

The .08% offense depends entirely upon the results of the breath machine (often called a "Breathalyzer", although there are many makes and models). These machines are notorously unreliable for any number of reasons. But a funny thing happens when your attorney tries to bring out those reasons for the jury. He tries to point out, for example, that the Breathalyzer computes the results by presuming that the defendant has a "partition ratio" of 2100:1 (the ratio of alcohol in the breath to the alcohol in the blood) — but that this is only an average: the defendant’s ratio is much lower, so the .09% reading should actually be .07%. However, the judge stops him: the law presumes that all men are average — even if they are not.

In fact, the Supreme Court of California has specifically ruled that such scientific facts are irrelevant. People v. Bransford, 884 P.2d 70 (1994). The Court justified its ruling in a rather frank — and amazing — justification: "It (.08%) will increase the likelihood of convicting such a driver, because the prosecution need not prove actual impairment…Adjudication of such criminal charges will also require fewer legal resources, because fewer legal issues will arise. And individuals prosecuted under such a statute will be less likely to contest the charges." In other words, ignoring scientific facts makes it easier to convict.

What about the officer who gave the breath test? Surely, we can question his experience and the way he administered the breath test. And this raises a prosecutrial favorite: the "Offical Duty Presumption". The California Evidence Code (sec. 664) puts it very simply: It is presumed that official duty has been regularly performed." Period. That’s it: Since it was the officer’s official duty to give the test, the law presumes he was qualified and did it correctly. And the burden is on the defendant to prove he didn’t. Interesting twist on the presumption of innocence, huh?

Well, so much for the .08% charge. At least the defendant is presumed innocent of the DUI charge, right? Wrong. The laws of most states create a presumption of guilt: if the Breathalyzer reads .08% BAC or higher, the jury will be instructed that the defendant is legally presumed to be under the influence of alcohol. That’s right: the defendant is presumed guilty. This is called a "rebuttable presumption" — that is, the defendant can try to rebut this presumption with other evidence. Put another way, he is presumed guilty and the burden is on him to prove his innocence. Just like in third world countries.

Ok, but the law says it’s illegal to have .08% BAC when driving — not when tested an hour later at the police station. If, for example, a person has a drink or two before driving, the alcohol will not be absorbed into the system for an hour or so: it will not be in his system while driving, but will be reaching peak BAC levels when tested an hour later at the station. So how does the prosecution prove BAC at the time of driving?

Easy: the law presumes the BAC is the same. Let’s take a look at California’s fairly typical law: "In any prosecution…it is a rebuttable presumption that the person had 0.08 percent or more, by weight, of alcohol in his or her blood at the time of driving the vehicle if the person had 0.08 percent or more, by weight, of alcohol in his or her breath at the time of the performance of a chemical test within thre hours of the driving." Well, now, that’s really amazing. The Legislature simply passed a law against scientific truth. We can absolutely say, with scientific certainty, that the BAC will NOT be the same for three hours after the test.

So much for the "presumption of innocence" in a DUI case….