Liable for what? What defines whether they are "doing otherwise"?
You have a better suggestion?
Do I have a better suggestion for what? The law?
Shall we simply whine endlessly about their malfeasance, or shall we do something substantial about it?
1)Stop buying and advertising in any paper you don't like.
2)Try to get as many people to do the same.
3)Start an alternative paper/network and counter the BS.
Suing them for frivilous stuff is NOT substantial and definitely not productive. You won't find a good attorney to take a case he knows he might sanctioned in.
Here are a couple of possibilities others have suggested:
As far as false advertising goes, if they promise potential customers that they don't have a political agenda, and a rat on the inside can be found to testify that they do, then that's false advertising under law.
You may be content to let them freely engage in sedition without opposition, but I for one will seek any method available to stick it to them as long as their behavior remains the same.