I dislike Fox News and breitbart as much as the next decent American and I think congress can certainly weigh in, but I wouldn't outright give them the power to determine what is and isn't fake news. If they took a vote now, it would likely go by party line and that would validate Trump's lies. Perhaps determination is best left for historians, scientists, the courts, and voters. I feel like everyday citizens can play a large role in stopping the propagation of lies as well. If you hear someone lying or spreading fake news, say something.