Since mid-May, President Obama and his campaign have been attacking Mitt Romney for "shipping U.S. jobs overseas." They've suggested he made false filings to the Securities and Exchange Commission. And they've hit him for having "Swiss bank accounts and offshore investment funds in the Caymans." Before considering their political impact, let's review each of these charges.

The first allegation-that Mr. Romney "shipped jobs to China and Mexico"-was called "misleading, unfair and untrue" by the Washington Post fact checker and labeled "bunk" in an editorial. The Annenberg Center's FactCheck.org said it "found no evidence to support the claim that Romney...shipped American jobs overseas."  Neither has anyone else. But Mr. Obama has not backed down, with his campaign spending more than $30 million to run TV ads on the subject for nearly three months.

The second charge-with its implied suggestion that perhaps Mr.