Former Massachusetts Gov. Mitt Romney (R) on Tuesday defended his decision to change his mind on abortion when he was governor. Romney campaigned as a pro-abortion rights candidate and maintained that position throughout much of his governorship. But the 2008 GOP presidential candidate said that he had a change of heart because of a bill that was considered that would have allowed human embryo research. Republican and Democratic opponents of Romney used his switch on the campaign trail to paint him as a flip-flopper who has no core principles. But Romney, who is presumed to be a 2012 presidential hopeful,...