The U.S. Eighth Circuit Court of Appeals is among the latest courts to consider whether the police need a legal justification in order to swipe someone’s credit card. In a June decision, it took the popular view that examining a card in this way isn’t a Fourth Amendment “search.” According to this position, there’s no real difference between looking at the information on the front of a card and using a device to examine the magnetic strip on the back of it. (United States v. DE L’Isle, No. 15-1316 (8th Cir. 2016).)
To the Eighth Circuit and several other courts, an officer doesn’t need a warrant or other legal justification in order to swipe or scan a card. An officer who has legitimately accessed a card—as opposed to one who has, say, arbitrarily stopped someone on the street and snatched the card away—can run it through a machine in order to investigate its legitimacy.
In the case that led to the ruling, law enforcement came by a stack of credit, debit, and gift cards during a search after a traffic-stop-turned-arrest. Suspicious, as they tend to be when encountering big bunches of cards, officers scanned the plastic. The scans confirmed their suspicion of identity theft, exposing the cards as having either stolen information or no account information at all.
For more on the case, including the court’s rationale and potential differences in court rulings on this issue, see Can the Police Swipe or Scan Your Credit Card?