>I once swerved to miss a squirrel in DC. (Oh, the jokes that could be made! <g>) The cop only saw the swerve and pulled me over. There was no specialized unit at all. I had to walk a line and blow into the breathalyzer on the spot.
>
>The look of utter disappointment on the eager cop's face when the reading was negative was worth the experience. It was all I could do not to bust out laughing. He looked like he'd just learned the truth about the Easter Bunny. LOL
>
>Perhaps that kind of experience is why they now have specialized units.

Back home, before they had the breathalyzers, you had to blow the bag and turn the crystals green. If they don't turn green, the cop pays for the crystals out of his pocket, which is why they first ran any old walk-the-line, close-yer-eyes + spread your hands + connect your thumbs, count from hundred backwards etc etc just to make sure you really are drunk.

Of course, there were always smart guys who did a good act pretending to be stiff drunk, and then go zero on the crystals. Sometimes, cop would waste two or three before getting the joke...

On the other end of the spectrum there's a guy who blows 3.45, cops almost faint, show him the reading, and the guy just says "quarter to four... cool, I'll be on time for work".