By Sarah Fenske

Any time I write about law enforcement issues, I get a spike in my inbox -- there are lots of you New Times readers who take civil liberties seriously, which is heartening. (There are also apparently a boatload who've been wrongfully arrested, which is not heartening at all.)

My column last week was about Heather Squires, a 29-year-old Gilbert woman who was arrested for drunk driving, despite having a 0.00 blood alcohol content. I found Squires' story horrifying: Either she was targeted because her husband is a DUI attorney, or some police officers literally cannot see the difference between a drunk and someone who's stone cold sober.

Either possibility is frightening.

And now one local expert has weighed in, suggesting the problem may be the latter option -- that the cops really are rounding up sober drivers. "The Forensics Guy" is a criminalist who used to analyze blood tests for the Chandler police department. (Today he runs an independent lab.) In this blog post, he suggests that as many as 15 percent of all blood tests come back below the legal limit.

That's really frightening stuff. (How many of those people had the charges dropped without having to hire a lawyer first? I'm guessing not many.)

But the Forensics Guy offers this advice for anyone who does get pulled over:

"The important part to remember from this article is that in Arizona at least, you do NOT have to perform [Field Sobriety Tests], and you really shouldn’t. There are no criteria for “passing” FSTs. There are only criteria for failing them. And if you don’t “fail” the results are “inconclusive”. ... Don’t make your defense any harder than it already is going to be by giving them ammunition."

Duly noted ...