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Tag Archives: breathalyzers

Is There a DUI Double Standard for Women?

In my previous post, “Are Women More Likely To Be Convicted of DUI?”, I discussed how today’s drunk driving laws and evidence tends to discriminate against women — specifically, I cited a scientific study showing how the lower levels of the enzyme dehydrogenase that breaks down alcohol are lower in women.  However, this is just one example of the problem. In another study, scientists found that women have lower “partition ratios” of blood to breath.  All breath machines in DUI ... Read More »

Do Breathalyzers Measure Alcohol?

Breathalyzers don’t actually measure alcohol. That’s right.  What they actually detect and measure is any chemical compound 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 in a DUI case will “see” all of those chemicals as alcohol — and report a falsely high blood-alcohol concentration (BAC). Most breath machines used ... Read More »

Rising Blood Alcohol Levels in DUI Cases

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 after a DI arrest at a police station. In other words, just because a breath test shows a level of, say, .09%, it does not mean that the blood alcohol level when the suspect was driving an hour earlier was the same .09%. So what was the blood alcohol level ... Read More »

Are Asthmatics Criminally Punished for Inability to Provide a Breath Sample?

Almost all states now have increased penalties for refusing to submit to blood-alcohol testing, usually involving added jail time and/or longer license suspensions. A few states even make refusing a separate and distinct crime. A large percentage of those charged with “refusing” are innocent. One of the most common refusals is the failure to breathe hard enough to produce a breath sample. The various breath machines all require the suspect to breath through a narrow breath tube hard enough to ... Read More »

Breathalyzers and the “Mouth Alcohol” Problem

One of the most common causes of falsely high breathalyzer readings is the existence of mouth alcohol. The breathalyzer’s internal computer is making a major assumption when it captures a breath sample and then analyzes it for blood alcohol concentration (BAC): It assumes that the alcohol in the breath sample came from alveolar air — that is, air exhaled from deep within the lungs. Since we are trying to measure how much alcohol is in the blood, rather than in the breath, the ... Read More »