I think in most places what they actually bust you for is possession. Although it’s hard to consume a drug without having possessed it.
Here’s a link
The most important federal statute dealing with illicit drugs is the Controlled Drugs and Substances Act (CDSA), which was proclaimed into force in May of 1997. There are six common offences under it: possession, trafficking, cultivation, importing or exporting and "prescription shopping" (obtaining multiple prescriptions by visiting several doctors)
I think that US laws are similar. In theory, the only time you would get into legal trouble for failing a drug test is if you’re already on probation
