Why does cable news have such a Liberal bias?

The broadcasters are liberal but, those that own the companies by and large are not. Also, it depends on the form of media you are talking about Radio is very conservative and the papers tend to be fairly liberal and less controlled. It is funny that you picked the media source that is the most regulated. There is much more bias in print and radio. T.V. for the most part, with exception of one news network, "He who shall not be named" (Harry Potter), is controlled. They don't really get outlandish with their coverage, they seem to at least try to make an effort to cover issues. However, most of the time it comes out as mindless distraction about J-Lo's baby bump.