It’s illegal, just like the states that first legalized marijuana were. The federal government lays off, seizing a random few shipments. When your drug is on patent, it’s the way to go. Companies like Allergan set up identical process factories in Europe. They purposely don’t fill in the last set of paperwork that would legalize the factory output for export into the U.S. That’s the flimsy mechanism that lets Customs do some window-dressing regulation. Had a problem once, during the Trump Admin. Customs seized a box. I got a nasty, semi-form letter from them. My prescription was replaced at no cost by my mail order provider. They said, “It’s random. Don’t worry about it.” Cost of doing business.