Florida DUI Lawyer: Breath Test Results Vary With Technique

The following article was written by a Florida DUI lawyer about how to, and how not to, undertake a breath test during a DUI stop or arrest – which was forwarded to me by a colleague in Florida. Obviously, I cannot vouch for its scientific accuracy, so take it for what its worth:

“Stop breathalyzer abuse: Seems that they don’t tell you everything whey they tell you to blow into the machine… ”

By Tom Hudson

The last thing I want to do is to tell drunk drivers how to “beat” the Intoxilyzer. But I am tired of seeing the police misuse the Intoxilyzer to beat up on the citizenry. So the following advice is how to get the Intoxilyzer to measure exactly what it’s supposed to measure: Your breath alcohol. And if it does that, you will probably be under the legal limit.

The police are trained to operate the Intoxilyzer. They take a 24 hour course, and are awarded a certificate that says that they are trained to be “breath test operators” under Florida law. I’ve taken that course, and have one of those certificates.

When the police are trained, they are instructed to tell the subject to “keep blowing until the tone stops.” In reality, you cannot keep blowing until the tone stops. Why not? Because the tone doesn’t stop until you are out of breath. It is a trick, to try to get you to blow out your deep lung air. Why are the police taught to do that? It turns out that the last fraction of a second of the breath is all that the Intoxilyzer measures.

Your “vital capacity” is the amount of air you can exhale from a full inward breath until you cannot blow any more. The lungs of a healthy human being have a typical “vital capacity” of around four and a half liters. That’s 4,500 milliliters. The breath chamber of the Intoxilyzer 8000 is approximately 31 milliliters. In other words, the breath machine measures less than the last 1% of your breath. (Actually the last .6%)

They are measuring only the last 1% of your breath!. That would be fine if the last 1% were a representative sample of your breath alcohol.

But it’s not.

The last 1% of your breath contains the highest alcohol concentration of your entire breath. By telling you to blow until you are out of breath, and measuring only the last 1%, the standard instructions for the Intoxilyzer can overestimate your breath alcohol by as much as 400%.


So how do you stop the police from overestimating your breath alcohol? Two steps. Remember this: Three and Two. That’s the number “3” and then the number “2”.

Step One. Take 3 deep breaths before you blow. If you hyperventilate three times before you blow into the machine, you will reduce your breath alcohol by as much as 55%. This occurs for two reasons. First, the breaths cool off your lungs. When the lung tissues are cooler, less alcohol goes from liquid form into vapor. The result is a lower breath alcohol. Second, the breaths clear out the alcohol from your lungs, filling them with fresh air. Find out more in this scholarly article.

(By the way, the reverse is also true. If you hold your breath for a few seconds before you blow, your breath alcohol will be increased. So whatever you do, DON’T HOLD YOUR BREATH before you blow into the machine!!)

Step Two. Blow out HALF of your breath and STOP. Half of a breath is all that you need to give a valid sample under the Florida protocols. The Intoxilyzer 8000 requires only 1.1 liters of breath to register as “adequate volume.” Blowing the minimum required can reduce your measurement by another 30%. How does it do that? By avoiding that alcohol-saturated “deep lung air” that the police are trained to test. The statutes do not tell them to test “deep lung air.” The statutes tell them to test “breath.” So why do they test “deep lung air” instead? Because that’s where the most alcohol is! It is a fraud, plain and simple!

So….. does this work?

I have personally, after a few drinks (all in the name of science, mind you) blown into an Intoxilyzer and obtained a reading of .099. That is over the legal limit. About three minutes later, I took my own advice and blew into the Intoxilyzer after three deep breaths. And blew only half of my breath. The result? A breath test reading of .028.

There you have it. The 3-2 Rule. You can blow an adequate sample under Florida law, and not allow the police to skew your sample so it looks higher than it really is. Sometimes blowing smart is a lot better than refusing to blow at all.

But even with all of this knowledge, the best way to avoid a DUI is not to drink and drive. Period.”

– John H. Bryan, West Virginia Attorney.

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