U.S. Border Patrol agents across ranks and regions routinely referred to unauthorized migrants using the derogatory slur “tonk‚” according to emails and text messages disclosed to HuffPost under the Freedom of Information Act. Higher-ups in Washington and within the Border Patrol itself have told agents that discriminatory and racist language undermines the agency’s mission — at times singling out the term “tonk” specifically and threatening disciplinary action for its use. But its use...