DUI Poll

I didn't know about that extrapolating back stuff. Interesting. Once it was winter and I'd been sitting in my car with the windows just barely cracked because of the cold, and using a solvent to remove some icky gung that a child had spilled all over my car. I finished the job and drove my car up to a spot where I used to like to go for walks. I walked maybe 100 feet from my car when the police drove up and waved me back to inform me that I was tresspassing on private land (the property had changed hands and the new owner was a Nazi). I had forgotten my license and they couldn't find me on their computer, so they took me down to the station to run me from there. At the station they gave me a BAC test and it came up something like .02 - must have been because of those fumes. I'd had nothing to drink for literally days. But I suppose they could have extrapolated back that somewhere in the day I started out with a picture of margaritas. How can that extrapolation stuff be legal?