Actually, we don't need Mitt's tax return. When he said he paid only 15% he did himself a lot of damage. And I'm sure Mitt has that right. He makes his money by selling stock or cashing in stock options, rather than taking a salary. And selling stock is perfectly legitimate capital gains. I ought to know, I spent plenty of time in the past figuring capital gains on my stock sales. A guy like Mitt shouldn't be paying more than capital gains rate (15%) unless his tax accountant is brain dead.
Mitt would have done better to just release his tax returns without comment. Few newsies are intelligent enough to read a form 1040 or schedule D and they might not have noticed that most (perhaps all) of Mitt's income was from capital gains.
A better public debate would be about having capital gains at all. Why not tax money made by playing the stock market the same as money made any other way?