Opponents point out that the tax code will become less progressive, exacerbating income inequality.

ECONOMIST: George Bush's tax agenda: Handing it back | The

But while the progressive income tax has continued to reduce inequality, it has not kept the gap in after tax income from fairly steadily widening over the 1987 to 2009 period, the researchers found.

FORBES: New Study Using IRS Tax Data Shows Rich Are Staying Richer, Poor Poorer

Progressive taxation is not the sole solution to extreme economic inequality in the US, but it can mitigate its effects.

FORBES: Why we Should Raise Taxes on the Rich (Debate Recap)