Clarence Thomas, alone but correct

Justice Thomas, dissenting:

Respondents Diane Monson and Angel Raich use marijuana that has never been bought or sold, that has never crossed state lines, and that has had no demonstrable effect on the national market for marijuana. If Congress can regulate this under the Commerce Clause, then it can regulate virtually anything–and the Federal Government is no longer one of limited and enumerated powers.

See my colleague David Bernstein's post at Volokh for more.