AFAIK it is state level in the US. Until a law is tested in court it is both enforceable and unenforceable. Posturing can have the desired effect though. Until this twitter suit plays out nobody can say whether the boycott was illegal or civil suit worthy.
I find it kinda weird that lawyers can't agree on that. It's hard to believe that it's that unprecedented.
As described to me, it sounds as if the law is unclear, and it's up to the random assignment of a judge to pick an answer.
As a logician I have always been deeply uncomfortable with what is called "legal reasoning". It bears little resemblance to my field. Which would be fine, if they just admitted that they really just mean it's a coin flip rather than pretending that you have some kind of security in consistency.
Has that ever actually been enforced? Or is it just posturing?