There is not sufficient binding precedent to clearly establish that revocation of supervised release because of drug use violates the Eighth Amendment; revocation was therefore not plain error.
http://media.ca1.uscourts.gov/pdf.opinions/17-1797P-01A.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.