With a bunch of specific exceptions, violence is handled by the states, so it depends on the state in which it occurred. My best guess is that it's some kind of criminal offense in all 50.
You claim that packets always cross state lines because sometimes they cross state lines. That's not a logically consistent statement.
> 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.