When Senator John McCain was running for president in 2008, his campaign experienced turbulence over an issue currently vexing the campaign of Senator Ted Cruz: the phrase in the Constitution stipulating that the president must be a "natural born citizen."
There are conflicting legal views (naturally) about what that means. Law professor Gabriel Chin of the University of California at Davis wrote a paper arguing that McCain's birth outside U.S. borders, in the Canal Zone, made him ineligible for the presidency. Donald Trump, a birther's birther, is now making a similar claim about Senator Ted Cruz. As my Bloomberg View colleague, Harvard law professor Cass Sunstein, wrote this week: