Question: I was driving through Marietta, coming home from an Atlanta Braves game, and I got arrested for a DUI. The Cobb cop said I swerved and he saw me and then he arrested me. Actually, before he arrested me he made me do some tests outside my car and then he gave me a breath test and then he arrested me. So I know I'm facing a DUI in Cobb County, Georgia, and I could use some help and I have some questions.

I was drinking at SunTrust Park during the game; not a lot of drinking, as I remember, but some. I had maybe eight beers over the course of the game and a couple of mixed drinks. But remember, I was there for nine innings of baseball that lasted over two hours, so maybe it wasn't that much alcohol. Anyway, I didn't feel drunk, not that that matters.

I was with a few friends from work, actually people I work with in my tattoo business. It was me another tattoo artist, a body piercer, and a guy who I know who sells tattoo equipment overseas. Before the game we smoked some pot, got pretty stoned, and then went to the stadium and, like I said, did some fairly light drinking.

I didn't eat much at the ballpark, just a pretzel with mustard. I'm thinking that had something to do with getting a little more drunk than I should have.

So when I was driving home I was listening to some country music and XXXtentacion, and I felt really bad because he was killed, so I got a little emotional and that's probably when I swerved and the cop saw me. I'm a good tattoo artist so I'm pretty emotional and after smoking marijuana and drinking and listening to music I felt depressed, and I don't think I focused on my driving and I swerved.

Sorry for writing so much but I want to know from a great Cobb County DUI lawyer why the cop gave me two breath tests, one outside my car on the road and one at the jail. That part doesn't make sense to me because my other DUI arrests they never made me do two breath tests.

C.L. in Marietta, GA

Answer: The breath tests you did were actually performed on two different machines and have different value to law enforcement and DUI defense attorneys alike.

Intoximeter, Alco-Sensor, Preliminary Breath Test (PBT), or Preliminary Alcohol Screening test (PAS)

The breath test administered on the street by a law enforcement officer is usually known as an Intoximeter, Alco-Sensor, Preliminary Breath Test (PBT), or Preliminary Alcohol Screening test (PAS). Unsurprisingly, the manufacturers of these products claim they are reliable and accurate. They are handheld and easy for a police officer to administer to a suspect. The companies that sell them claim they are useful for law enforcement and personal use and workplace testing.

Alco-sensors are not, however, admissible in Georgia courts for the specific alcohol reading provided. But they are admissible for whether a person tests positive or negative for alcohol.

The Intoxilyzer

But the reading from an Intoxilyzer is, however, admissible in a Georgia court. An Intoxilyzer is generally a larger machine than an Alco-Sensor and it is usually administered in a jail, at a police station, or at another law enforcement location.

The Science Behind the Breath Test

As far as the science is concerned, this device uses infrared (IR) spectroscopy, which identifies molecules based on the way they absorb IR light. Basically, to identify ethanol in a sample, you have to look at the wavelengths of the bonds in ethanol and as accurately as possible measure the absorption of IR light. The absorbed wavelengths help to identify the substance as ethanol, and the amount of IR absorption tells you how much ethanol is involved.

As a Practical Matter

As a practical matter, a police officer or a deputy sheriff will try to administer both the Alco-sensor and the Intoxilyzer. But they would rather get an Intoxilyzer reading because the reading from that test (.04, .13, or .24, for example) is admissible in court.