Mitt Romney filed his tax returns following IRS rules, that is the beginning and end of this stupid story, investment income has ALWAYS had favorable rates under the tax code since its inception. There is a clear reason for this; it is the result of capital investment the heart and soul if the American economy.
Mr. Romney gets a significant part of his income as long term capital gains (taxed at 15%) thru the “Carried Interest” rule. Carried Interest is a tax maneuver that allows hedge fund and private equity managers to receive what is essentially compensation as investment income; they are allowed to “share” in the profits they generate for their clients. There is almost no reasonable basis in the tax code for this, and the Internal Revenue Service has fought this for years, it is a loophole virtually any way you look at it BUT that is the current law of the land as defended vociferously by the New York Democratic congressional delegation. My issue with carried interest is that these fund managers receive comparatively little straight compensation and that is what makes it egregiously wrong. I think the correct path would be a mix of W-2/Compensation and Carried Interest, a meaningful % of their income HAS to be traditional compensation at normal tax rates. But the bottom line is Mr. Romney did not make these rules and has not lobbied for them and simply followed the tax code in effect. It also appears to me that Mr. Romney no longer provides "services" to Bain Capital so it seems mostly correct to me that virtually ALL his income would be in the form of investment and 0 in compensation (in his case).
The other phrase that gets thrown about in this discussion is the term “fair share,” usually directed towards the “other guy” who is not paying his! Interestingly it is never directed at the almost 50% of Americans who routinely pay NO federal income tax. I am sad to say, in my opinion, the term "fair share" and taxes NEVER belong in the same sentence. The reason is that the tax system is so complex and corrupt that I don't know how you apply the word "fair" to it in any circumstance, one is either filing a correct and honest tax return (as did Mr. Romney) or you don’t – “fair” does not enter into it.
One final political thought on Mr. Romney; Newt Gingrich is so corrupt and debased that he makes Romney look like a school boy, if Republicans nominate Gingrich they will rue the day, I suspect Obama would eat him for lunch!