When Missouri parents Tiffany and Anthony Swearengin saw their children weren’t making progress in school, they followed the lead of millions of American families: They notified the school, took their kids out of class and started homeschooling. Then the Swearengins received a letter from Rose Pursell, the chief deputy juvenile officer in the Douglas County, Missouri, court system, notifying them “to appear before the Truancy Court of 44th Judicial Circuit, at the Juvenile Court Center.” The letter threatens the parents with the “above named juvenile be[ing] placed in the legal custody of the Missouri Children’s Division.” But no such court...