During your DUI arrest, you were asked to blow into a machine called a breathalyzer. It's a breath testing machine. And it's important to your case that you know a little bit about it. Because it's a significant–maybe the most significant–piece of evidence against you, used by the prosecution to convict you.

You see, the score which it comes up with presumably indicates that you were “impaired” when you blew into the machine. In California the magic number is .08 or higher.

But exactly how does a breath machine calculate you level of impairment if the breathalyzer is testing your breath? After all, you drank the alcohol; you didn’t breath it.

To better understand this let's start with your body. After you consume alcohol, be it wine, beer or otherwise, it gets absorbed from the mouth, throat, stomach and mostly from the intestines into your bloodstream.

As the blood travels through your body it (obviously) travels to your brain which is why you feel the effects. It also travels through your liver where it immediately begins the process of removing it from you blood stream.

In addition, the blood travels through your lungs. There, some of the alcohol molecules move across the membranes of the lung into the air, using the same process that allows you to breath in the oxygen you need to live.

At this point your lungs contain alcohol molecules along with molecules of oxygen etc. and the concentration of alcohol molecules in your lungs is related to the concentration of the alcohol in your blood.

The government asserts that the alcohol in your breath is related to the alcohol in your blood at the ratio of 2,100:1. Meaning that 2,100 milliliters (ml) of air will contain the same amount of alcohol as 1 ml of blood. But this ratio is a standard number and who is to say that this ratio is applicable to you?

Now that we know how the alcohol passes through your body we can examine what this machine does. The “breathalyzer” uses infrared (IR) technology to presumably identify alcohol molecules based on the way they absorb light and the machine uses this to calculate the final result that you will see on your arrest report.

But for a number of reasons the breathalyzer results can be inaccurate. And this inaccuracy can be used by a DUI attorney to show that you actually were not impaired when you were arrested.

There's a lot more to understand about how California uses the breathalyzer, and I'll be glad to explain it to you during an initial free consultation about your DUI case. Simply call me at 1-877-638-4435 today to schedule your free consultation so you can learn how you may be able to keep your license and your freedom.

For more specific information on this see: http://science.howstuffworks.com/breathalyzer4.htm.