Prepaid debit cards are used by people who don’t have bank accounts but want the convenience of paying for things with a card. They’re typically used by low income Americans. You load the thing up with money, then you can use however much money you put on the card.

They’re pretty common, with prepaid card companies reporting $220 million in sales in 2014 and a 50 percent increase in their use between 2012 and 2014. Furthermore, many people get paid by their employer using prepaid cards.

The OHP has been using the ERAD device for over a year, without most of the public knowing it, and there could be major constitutional problems at play here.

Matt Miller, managing director at the Institute for Justice, told The Daily Beast that many people use prepaid cards as if they are bank accounts, and an officer scanning your prepaid card is essentially getting access to what you use for a bank account. “I think that’s hugely constitutionally problematic,” Miller said. “There’s a huge Fourth Amendment concern there, because you’re just accessing someone’s bank account without a warrant.”