A year ago, in Action Comics, Superman declared plans to renounce his U.S. citizenship. "'Truth, justice, and the American way' — it's not enough anymore," the comic book superhero said, after both the Iranian and American governments criticized him for joining a peaceful anti-government protest in Tehran. Last year, almost 1,800 people followed Superman's lead, renouncing their U.S. citizenship or handing in their Green Cards. That's a record number since the Internal Revenue Service began publishing a list of those who renounced in 1998. It's also almost eight times more than the number of citizens who renounced in 2008, and...