Fox is again attempting to redefine fairness, this time by pushing the GOP-favored flat tax in the midst of debate over the Buffett Rule, which would set a minimum effective tax rate for millionaires. The flat tax is a plan Republicans have been trying to establish as far back as the 1990s.

Following the release of President Obama's tax returns, Fox jumpstarted its push for the flat tax, insisting that it would be a fairer tax system. But this is just the latest attempt by Fox to redefine “fairness” as a tax system that experts contend is designed to favor wealthier taxpayers.

Prior to an interview with Romney campaign adviser Eric Fehrnstrom, “straight news” anchor, Martha MacCallum asked her Twitter followers, “Should Mitt Romney go further with tax reform?” She then added: “Flat tax anyone?”

On her “straight news” show, MacCallum continued to advance the idea of a flat tax, saying to Romney senior adviser Eric Fehrnstrom, “So, essentially, you're talking about flattening out the tax code and making the rules more sort of across the board for everybody so that there will be fewer deductions, fewer loopholes, all of those sorts of things.” She then asked: “Why not -- you know, I get Twitter messages from so many people who say why won't Mitt Romney back some form of flat tax? Why won't he?”

MacCallum, even though she falls into what Fox calls its “straight news” programming, has repeatedly pushed for the GOP's idea of a flat tax. And she's not alone. Just the day before, Fox Business' David Asman had praised the “fairness” of the flat tax during an episode of Happening Now. Asman repeated the incorrect claim that “46 percent of Americans pay no taxes at all,” adding that a flat tax would be “more of a fairness,” though it would raise taxes on those Americans who can least afford it.

Republicans have been pushing for a flat tax since as far back as 1996 when Steve Forbes sought the GOP presidential nomination with a flat tax proposal as part of his platform. More recently, Republican presidential candidates Herman Cain, Rick Perry, and Newt Gingrich have all proposed different types of flat taxes, each of which was granted a friendly platform on Fox to expand their ideas.

Herman Cain's 9-9-9 plan in particular got the kid gloves treatment from Fox, which chose to ignore the impact his proposal would have on working-class Americans. Instead of reporting the fact that Cain's tax plan would make “some poorer Americans pay more into the system,” as PolitiFact noted at the time, Fox contributor Neal Boortz brushed the tax hikes aside, saying low-income Americans are “probably still coming out ahead of the game no matter how low your income may be.”

Fox has repeatedly strived to cast doubt on the fairness of a progressive tax code by parroting the myth that nearly half of the working population pays no federal income tax. In fact, as one analyst noted, “no one lives tax-free in America.” Fox's “straight news” reporter, Jim Angle recently remarked, “For half of the working population, 'fair' means almost no income taxes at all.”

Fox has also pushed against the notion that millionaires should pay more in taxes, even though this is an idea supported by the majority of Americans.