It's reasonable to demand that opinion be called opinion. Protection for opinion and political speech remain under the First Amendment. Presenting something provably false in the eyes of any reasonableperson as objectively true is a crime against the public. Questioning the credibility of established "facts" is both fine and necessary, but the opinion being presented shouldn't be treated as objective fact for disingenuous reasons. Essentially if this is handled correctly, it would force a bit more intellectual honesty in public discourse through the media. There is of course room for debate as to whether or not government intervention is worthwhile. It certainly might not be. It's difficult to word the intent of such a law to target malicious propaganda without making it theoretically possible to stifle some legitimate discourse as well. On the other hand, anything disclaimed as opinion is probably untouchable anyway, as it should be.