Mitt Romney is running on his business expertise. His tax returns are a relevant window into how he conducts his business affairs. If he refuses to release them, it is because: one, he had a lot more money in tax shelters in prior years than he does now. Two, he did something shady. Or, three, he's stupid.
CNN's Erin Burnett, attacks Romney for not releasing his previous year's tax returns. She claims there can only be three reasons to want to hide tax returns for previous years.