D.C. Code § 48-904.08: Second or subsequent offenses.

(a)

Any person convicted under this chapter of a second or subsequent offense may be imprisoned for a term up to twice the term otherwise authorized, fined an amount up to twice that otherwise authorized, or both.

(b)

For purposes of this section, an offense is considered a second or subsequent offense if, prior to commission of the offense, the offender has at any time been convicted under this chapter or under any statute of the United States or of any state relating to a controlled substance.

(c)

A person who is convicted of violating § 48-904.06 may be sentenced according to the provisions of § 48-904.06 or according to the provisions of this section, but not both.