unconstitutional (2-1 decision), in US v Xavier Alvarez.

The majority raises an interesting discussion point:

The rule the government and dissent urge us to apply in order to uphold the Act would, if adopted, significantly enlarge the scope of existing categorical exceptions to First Amendment protection. All previous circumstances in which lies have been found proscribable involve not just knowing falsity, but additional elements that serve to narrow what speech may be punished. Indeed, if the Act is constitutional under the analysis proffered by Judge Bybee, then there would be no constitutional bar to criminalizing lying about one’s height, weight, age, or financial status on Match.com or Facebook, or falsely representing to one’s mother that one does not smoke, drink alcoholic beverages, is a virgin, or has not exceeded the speed limit while driving on the freeway. The sad fact is, most people lie about some aspects of their lives from time to time. Perhaps, in context, many of these lies are within the government’s legitimate reach. But the government cannot decide that some lies may not be told without a reviewing court’s undertaking a thoughtful analysis of the constitutional concerns raised by such government interference with speech.
There is (or at least "should be") a distinction between a law regulating speech (a lie of some kind) that is simply "unwise"; and another such law that goes further and becomes "unconstitutional". The question is where to draw the line in this "era of absolutism".

Remember the ancient First Amendment example of a constitutional law that prosecuted a person who falsely yells "fire" in a crowded theater.

The dissent by Judge Bybee (yes, he of co-fame with John Yoo and the memos) sums the situation as follows:

In sum, the better interpretation of the Supreme Court’s cases and those of our court is that false statements of fact - as a general category - fall outside of First Amendment protection except in certain contexts where such protection is necessary “to protect speech that matters.” If a false statement does not fall within one of these exceptions, the general rule applies. And even in the exceptional contexts, a false statement that is neither satirical nor theatrical is unprotected if it is made with knowledge or reckless disregard of falsity.
I'll cast my lot with the dissent on this issue.

Regards

Mike