"There are still glitches in it," Jacoby told ABC News. "That said, some system like this is absolutely imperative for a working immigration system."
As the administration expands the system, the pressure is on to make it work -- a fact that Homeland Security Secretary Janet Napolitano acknowledged in Senate testimony on Wednesday
"I believe E-Verify is very important and must be an integral part of immigration enforcement moving forward," Napolitano said. "So we know that, with incentives and otherwise, E-Verify can really make a difference. We are committed to making it better."
Ferdous Al-Faruque, Jason Ryan and Theresa Cook contributed reporting for this story.