For the first time in state history, the Colorado Supreme Court will hear arguments Thursday about whether animals are entitled to legal protections against imprisonment, including the right to challenge their custody. The Nonhuman Rights Project, a nationwide civil rights organization trying to secure legal rights for animals, is suing the Cheyenne Mountain Zoo in Colorado Springs on behalf of the institution’s five elephants in hopes of getting the animals released into a sanctuary that has not been identified under the writ of habeas corpus that protects people against unlawful and indefinite imprisonment. “‘Person’ is a term that attaches to any individual or entity possessing (or capable of possessing) a legal right,” the Nonhuman Rights Project wrote in its appeal.