When conservatives argue that capital is mobile, and that raising taxes in America will send rich Americans overseas, liberals often answer skeptically. They admit that raising state tax rates may cause rich people to move to other states. But picking up and leaving America seems more dramatic, not only for patriotic reasons, but even financially, because when you do it the IRS makes you pay taxes on all your capital gains, even those that would be considered unrealized if you stayed in America. The New York Times reported last year that the number of Americans leaving skyrocketed in 2010 and 2011. The latest data point, my former colleague Josh Gerstein reports at Politico, is oil heiress Anna Getty, a self-described libertarian who has apparently decamped to Italy from Los Angeles.