In May, now-ousted U.S. Attorney General Jeff Sessions announced the start of the Trump Administration’s “zero tolerance” policy to separate migrant families at the Mexican border. “If you are smuggling a child” into the country, he said , “then we will prosecute you, and that child will be separated from you as required by law.” In just six weeks, more than 2,600 children were taken from their parents or other adults. Although a federal judge ordered the government to reunite all children...