It's called the Federal Food, Drug, and Cosmetic Act (FFD&C). www.gpo.gov has it somewhere in the U.S. Code. Or try www.findlaw.com

That law gives FDA absolute legal authority to seize *any* drugs not manufactured in an FDA-approved plant ... as are almost all of the legend drugs coming in from overseas. But the only people prosecuted by the FDA (so far) were bringing in obvious commercial quantities. Seizure letters these days are beginning to be common on FDA letterhead.

Trampy

P.S. Saying that something is legal because you got ten packages is the same kind of logic as saying that police can't enforce the speed limit because many drivers are allowed to exceed it. Maybe the problem here is confusing statutory law with contract law. If someone has a civil contractual right against another that they fail to enforce, common law says that they can lose that right. This is not the case for statutory law; failure to enforce statutes is no legal grounds for overturning the statute. The law can be on the books for a hundred years and never enforced ... but that's no grounds for acquittal if a prosecutor decides to start enforcing that law. Enforcement of statutes is wholly discretionary.