Most purveyors of news value impartiality, neutrality, and objectivity, despite the inherent difficulty of reporting without political bias.
Perception of these values has changed greatly over time as sensationalized 'tabloid journalism' has risen in popularity. Michael Schudson has argued that, before the era of World War I and the concommitant rise of propaganda, journalists were not aware of the concept of bias in reporting, let alone actively correcting for it.
News is also sometimes said to portray the truth, but this relationship is elusive and qualified.