When does coke become crack?

The Supreme Court was asked this question today in DePierre v. United States.  The First Circuit found that the federal sentencing guidelines providing greater punishments for crack, or as it is called in the law "cocaine base" refers to all forms of cocaine base, not limited to crack.  The Plaintiff is arguing that the term cocaine base refers only to crack, because that is what Congress sought to penalize when it passed the law.  The US Government's position is that cocaine base is any cocaine you can smoke.