There's this little thing called the Constitution
You'd think a Republican Congressman would have heard of the First Amendment, but then again, these are strange days we are living in, so perhaps it is no surprise that Joe Barton, chair of the House Commerce Committee, is threatening television networks with legislation that would enforce objectivity. Who would decide whether that standard is being met? Remember when Republicans believed in small government?
Personally, I think news outlets should be free to dispense with objectivity, an impossible standard, so long as they disclose their biases. As Copeland points out, regarding the print media:
Do you know why newspapers are supposed to be objective? It has nothing to do with fairness. Following the Civil War, when more and more newsapers were falling into the hands of private ownership (as opposed to political party ownership), owners realized that leaning one way or another immediately offends half of your potential advertisers.
Fairness, not objectivity, should be the coin of the realm.