CBS gets a story from someone generally acknowledged to be a nutcase about President Bush's Texas Air National Guard service. Do they investigate or denigrate publically the source? No. Do they investigate the story? Kinda. Do they run the story? You betcha, and they use easily identified forgeries to do so.
CBS gets a story from a bunch of decorated Vietnam heroes about Senator Kerry's Vietnam service. Do they investigate or publically denigrate the source? You betcha, they do both. Do they investigate the story? Not really. To this day Sen. Kerry has not released all of his military records like Pres. Bush did. Do they run the story? Briefly, only after the story has spread through out the internet, and spend most of the time attacking the Swift Boat Vets.
And we are expected to believe there is no bias?