I don't think that a case can be made to force a newspaper to drop their liberal agenda. That said, such past behavior can be used to appeal to the government to halt any buyouts or mergers of newspapers that would drop a city to one daily paper.
Internet news is the antidote. There are minimal distribution costs compared to physical newspapers and TV NEWS. Drudge for the most part just repackages other sites' news, but he can make a story that is burried deep in the New York Times into the lead story on his website.