There is the "I know it when I see it" standard for pornography, which is equally dubious. If it was drafted as "knowingly consuming an unapproved substance for the purpose of intoxication", I could see that slipping through. But again, I'm not sure the support is there, but it would be another win for state power.
The real shame is, many of those synthetic drugs are actually more dangerous than the real thing.
The obscenity ruling was a bizarre sideways move for the Supreme Court, given their usual intense protection of the First Amendment. The "I know it when I see it" was even said almost tongue-in-cheek.
> The real shame is, many of those synthetic drugs are actually more dangerous than the real thing.
That, to me, is the real tragedy. These drugs are dangerous, and only going to get more dangerous as the "good" compounds are quickly banned, leading chemists to use less tested and more unusual compounds.
The real shame is, many of those synthetic drugs are actually more dangerous than the real thing.