An email from the Obama campaign encapsulates the problem when political campaigns seize the language of fact checkers, muddying the waters. In the note, sent later in the day today, Obama campaign deputy campaign manager Stephanie Cutter invites supporters to “report an attack” at the Truth Team report page. “Received a robo-call or an email forward full of falsehoods?” the page asks. “Found a misleading leaflet in your mail? Tell us about it, and help fight back against the attacks on President Obama and his record.” Cutter in her email hammers Mitt Romney for saying “Since President Obama assumed office...