Looks like the men’s restroom isn’t the only place where things are a little out of control at the Minneapolis airport. The U.S. Immigration agents at MSP are also taking a walk on the wild side, in a manner of speaking.

That’s the contention of one frequent flier who contacted me yesterday in the hopes of solving a mystery.

Before getting to his story, it should go without saying that Immigration agents don’t have an easy job. They determine if you can enter the United States or not, and if they happen to let another 9/11 terrorist into the country, let’s just say that could be a career-limiting move.

So they ask tough questions. They have to. But when do those questions – and their treatment of the passengers being processed – cross the line and violate your civil liberties and right to privacy?

Stephen Doggette, an IT manager from Dayton, Ohio, raises these issues in his account of dealing with the MSP officers earlier this week:

Yesterday as I returned from an overseas trip to Hong Kong (where I have been many times), I cleared immigration at Minneapolis-St. Paul. I received what I felt to be an aggressive and accusatory questioning that resulted in me being sent to the “red” line for further interrogation. My form had been marked with a red “B” upon my initial screening. When asked, nobody would explain tome what that red “B” meant.

I was told that it meant I had to stand in the red line and, upon further questioning, was told that I did not need to know what a red “B” indicated. I was asked what I believed to be irrelevant and outright intrusive questions, including my current salary.

I would like to understand my current “status” and results after this questioning. Over the last several years I have logged between 75,000 to 100,000 miles per year and am no novice to travel. To whom can I explain my version of the situation and file a complaint? Thank you for any help or direction you can provide.

The short answer is: the U.S. Citizenship and Immigration Services doesn’t accept e-mails from its site. You have to call (800) 375-5283 with a complaint. But I did a little more digging, and found an e-mail address — [email protected] — that might work.

The more interesting question, to me, is: Why would they send Doggette to the red line? I asked him if he had anything to declare (that’s what the red line is for) and he didn’t.

Also, why would you ask a U.S. citizen for his salary? What does that have to do with anyone’s immigration status?

More importantly, what does a red “B” stand for? Is this the equivalent of the dreaded “SSSSS” that directs the TSA to give someone additional screening – or something else?