Archive for May, 2007

How Accurate are Breathalyzers?

Monday, May 7th, 2007

With more than a little federal coercion, all states have now passed laws making it a criminal offense to drive with .08% alcohol  in your blood. And most people suspected of violating that law are given breath tests to determine their blood-alcohol concentration (BAC). The breathalyzer will take a small sample of the suspect’s breath and estimate how much alcohol is in it — and then estimate how much may be in the blood. And what that machine says is pretty much the end of it. There will be no second tests. There will be no cross-examination of the machine.

Just how accurate and reliable are these machines that we have permitted them to become judge and jury?

To begin with, scientists universally recognize an inherent error in breath analysis, generally of plus or minus .01% in the reading. That means that if everything is working perfectly (an unlikely scenario), a .10% breathalyzer test result can be anywhere from .09% to .11%. This has been acknowledged by courts across the country (see, for example, People v. Campos, 138 Cal.Rptr. 366 (California) and Haynes v. Department of Public Safety, 865 P.2d 753 (Alaska);  in State v. Boehmer, 613 P.2d 916 (Hawaii), the courts recognized an even larger .0165% inherent error).

What does that tell us about the accuracy of these breathalyzers? Well, let’s again take a test result of .10%. Taking inherent error into consideration — and assuming the machine was working perfectly, the officer administers the test correctly, and the suspect’s physiology is normal and perfectly average — the true BAC could be anywhere from .09% to .11%. In other words, the true BAC can be 10% in either direction — or, put another way, anywhere within a 20% margin of error.

These machines have a 20% margin of error?

That’s right. A person accused of driving with over .08% BAC can be convicted by a machine which, if everything else is perfect, has a built-in 20% margin of error. Would you be comfortable with an airline pilot who worked with a 20% range of error? A brain surgeon?  A bank teller?  How about the evidence in a criminal case where guilt must be proven beyond a reasonable doubt?

But it gets worse….

Most states have standards for breath testing. Although some states only provide for a single breath test, most require that two breath tests be given — and the results must be within a given range.  In North Carolina, for example, there must be two test results within any group of three which fall within .02% of one another; if they are .10, .07 and .13, for example, the officer must start over.  In California, the officer can continue giving tests for as long as it takes until he gets two consecutive results within .02%; results of .18, .10 and .12, for example, would be a valid result.

Think about that for a moment.  Let’s take that California example.  And let’s say the officer gets a .10% reading on a test.  What must the result of the next test be to be acceptable?  Well, it can be .08, .09, .10, .11 or .12 — that is, anywhere between .08% and .12%.

In other words, the acceptable range of error is 40%!  And based entirely upon this, a defendant can be convicted of driving with over .08% blood-alcohol — and, further, legally presumed guilty of the separate offense of driving under the influence.

In a country where the legal standard is “proof beyond a reasonable doubt”, the legal standard in drunk driving cases is “proof with a 40% margin of error”.

Close enough for government work. 

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The Hypocrisy Continues…

Friday, May 4th, 2007

MADD Award Winner Charged with DUI 

Cincinnatti, Ohio.  May 4  –  A Cincinnati police officer who received an award from Mothers Against Drunk Driving has been charged with drunken driving.

Police in nearby Aurora, Indiana, pulled over Specialist Charles Beebe this week after a motorist reported that he had forced two vehicles off the road. Beebe failed a field sobriety test. The arrest report says his blood-alcohol level was tested at point-oh-eight, which is considered legally drunk in Indiana. He has pleaded not guilty and is free on 15-hundred dollars bond.

Beebe received a Top Cop award this year from MADD’s Southwestern Ohio chapter.

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Field Sobriety Tests and Circadian Rhythm

Wednesday, May 2nd, 2007

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 around closing time and 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 — 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.”

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