The press has traditionally been regarded as a watchdog of democracy. The theory is that only by making facts and information widely available can democratic decisions be wisely made. Since the Vietnam War, however, many Americans have become disillusioned with the media. The press does have a clear leftist bias. It is not an overt bias.
Stories are fact-checked and most news stories are relatively free from errors of fact.
There does exist a selectivity bias, however. Editors decide to pursue certain stories in depth and not others. Accusations are given large play while defenses or even retractions appear in the back pages if at all. The quarrel is not with the facts, but with how the facts are presented and which facts are presented. The fact is, with journalism as with other things, personal prejudices and beliefs affect even the best-intended actions.