Last month, the ICE has its biggest immigration raid ever. Hundreds of undocumented workers were sentences, but not a single employer was called out by the law. As a result, critics are increasingly calling for employers to be held accountable, too:

"Until we enforce our immigration laws equally against both employers and employees who break the law, we will continue to have a problem with immigration," said U.S. Rep. Bruce Braley, an Iowa Democrat whose district borders Postville.

"Even if you wanted to pursue an imbalanced enforcement-first strategy, the only thoughtful way to do it would be to go after employers, make examples of them and try to scare other employers into compliance," he said. "They're not doing that."