This piece was published in partnership with The Intercept.

In Washington Heights, a hilly neighborhood at the northern tip of Manhattan, 128 P&L Deli Grocery is the busiest hub on the block. Outside, neighbors lounge in lawn chairs and pass around a hookah hose. Inside, customers watch baseball on an iPhone mounted behind the counter and sip tamarind juice through straws. Yucca, plantains, and bagged heads of lettuce loiter by the entrance.

Porfirio Mejia, the Dominican-born New Yorker who has owned this grocery for six years, seems to know everyone. He pats a few kids on the head and nods when a woman tells him she’ll pay him tomorrow. He pauses to inspect the peppers and tomatoes, remarking that a fresh produce delivery is due the next day. He works with the anti-hunger advocacy organization City Harvest to promote fruit and vegetable purchases, and he says that more than half of his customers buy their groceries with SNAP, the government assistance program formerly known as food stamps.

Well, they used to. The SNAP transactions at P&L tripped the wires of an algorithm that the U.S. Department of Agriculture uses to screen for fraud. Mejia’s decision to issue IOU’s to his regular customers — a policy that allowed him to deliver food to elderly neighbors and settle up after they received their benefits — triggered a suspicious activity flag in the system. By allowing customers to rack up a few weeks’ worth of grocery bills before paying with their benefit cards, Mejia violated the agency’s rules, which prohibit retailers from establishing informal credit systems with their customers.