It was a landmark day in the U.S. District Court in San Diego Monday. For the first time ever, a federal court is considering whether or not the 13th Amendment, which prohibits slavery, applies to five orcas—Tilikum, Katina, Kasatka, Ulises and Corky—who are now incarcerated at SeaWorld amusement parks. PETA, three marine-mammal experts, and two former SeaWorld trainers filed the suit in the orcas' behalf in October. SeaWorld filed a motion to dismiss the case—but that didn't happen today. Instead, Judge Jeffrey Miller said he will consider the case and will issue a ruling at a later date.