The coffee chain Dunkin' is suing and closing its franchisees found to be employing undocumented workers. Food writer Corby Kummer joined Boston Public Radio on Friday to discuss why the company is targeting its stores.

Franchisees had failed to use E-Verify, an online system that checks I9s against the Department of Homeland Security databases, when hiring employees according to Dunkin', Kummer said.

"All of Dunkins' are franchisees — 9,400 in this country. So the corporate office can sue or take away a franchise license for any number of reasons, this is just one of them."

Kummer questioned why Dunkin' is taking proactive action at this moment in time.

"What's the provocation? What are they worried about? Have they been threatened with lawsuits?" he asked. "One of the many dirty secrets about the food industry is it so heavily reliant on undocumented workers. Whether it's agriculture, food service, big farms, wherever — it is none too careful about checking documentation."

Kummer summed up the response that Dunkin' has had towards criticism over its crackdown.

"They say, to spin it maybe, that they are looking to have more legal exemptions and to bring over more students and to get more visas and maybe that's the reason. Maybe there's something else we don't know about."

Kummer is a senior editor at The Atlantic, an award-winning food writer, and a senior lecturer at the Tufts Friedman School of Nutrition and Policy.