In 1988, federal prosecutors in Chicago charged Rodrigo Mejia with cocaine trafficking. At trial, a drug enforcement agent testified that surveillance of Mejia’s home began with an informant’s tip to police that a “shipment” was expected to arrive at the house. The trial court admitted the agent’s testimony about the tip over a hearsay objection.After Mejia’s conviction, the 7th U.S. Circuit Court of Appeals upheld the lower court’s ruling, reasoning that the informant’s out …