Notice how all that hot anti-immigration rhetoric seems to have cooled lately? Not entirely, of course. Lou Dobbs is still frothing on CNN. And one of Lou’s frequent guests, our very own Kris Kobach, raised the topic this week in announcing his bid for Kansas secretary of state.

Otherwise, we haven’t heard a lot about immigration since the economy went south — partly because the downturn eliminated many of the jobs that illegal immigrants had filled.

That’s a telling reminder that it isn’t the illegal immigrants who are at fault so much as it is the people who employ them.

An extreme example was detailed in this week’s federal indictment of a human-trafficking ring based in the Kansas City area.

Twelve people were charged with racketeering, human trafficking and immigration violations for supplying hotels and other businesses in 14 states with hundreds of workers.

Most of those workers were in the country illegally and were treated like slaves by the labor-leasing companies.

According to the feds:

Many of their employees were allegedly victims of human trafficking who were coerced to work in violation of the terms of their visa without proper pay and under the threat of deportation. The defendants also required them to reside together in crowded, substandard and overpriced apartments.

If you read the 90-page indictment, you’ll be reminded as I was of history classes where we learned about the illegal sweatshops in the garment industry of a century ago.

Only instead of sewing clothes, most of these modern-day sweatshop workers toiled as housekeepers in swanky hotels.

Mind you, the hotels and other end users were not indicted. After all, they were assured by the leasing firms that everything was legit.

Still, I wouldn’t call them victims, either. Surely, someone at some level wondered why their hotel or construction company was getting the labor so cheap.

The Justice Department declined to comment.

But Mark Lagon did weigh in.

Until January, Lagon was the State Department official in charge of the effort to combat human trafficking..Now he heads the Polaris Project’s effort to end human trafficking worldwide.

 “The employers are responsible for knowing whether the laborers being brought to them are legitimate,” Lagon told me.

Although acknowledging that it isn’t always easy for an employer to know whether a labor-leasing company is telling the truth, Lagon said that cases like the one in Kansas City point up the need to make the extra effort.

He supports a system that would help businesses become more responsible. One that would put the stamp of approval on labor suppliers that play by the rules.

“We need some sort of vetting process,” he said.

Until that happens, there’ll be more cases like this one making headlines.