(a)    Except as otherwise provided in this section, a person who violates a provision of §§ 5–602 through 5–606 of this subtitle with respect to a Schedule I or Schedule II narcotic drug is guilty of a felony and on conviction is subject to imprisonment not exceeding 20 years or a fine not exceeding $15,000 or both.

(b)    A person who is convicted under subsection (a) of this section or of conspiracy to commit a crime included in subsection (a) of this section is subject to imprisonment not exceeding 20 years or a fine not exceeding $15,000 or both if the person previously has been convicted once:

(1)    under subsection (a) of this section or § 5–609 of this subtitle;

(2)    of conspiracy to commit a crime included in subsection (a) of this section or § 5–609 of this subtitle; or

(3)    of a crime under the laws of another state or the United States that would be a crime included in subsection (a) of this section or § 5–609 of this subtitle if committed in this State.

(c)    (1)    A person who is convicted under subsection (a) of this section or of conspiracy to commit a crime included in subsection (a) of this section is subject to imprisonment not exceeding 25 years or a fine not exceeding $25,000 or both if the person previously:

(i)    has served at least one term of confinement of at least 180 days in a correctional institution as a result of a conviction:

1.    under subsection (a) of this section or § 5–609 or § 5–614 of this subtitle;

2.    of conspiracy to commit a crime included in subsection (a) of this section or § 5–609 of this subtitle; or

3.    of a crime under the laws of another state or the United States that would be a crime included in subsection (a) of this section or § 5–609 of this subtitle if committed in this State; and

(ii)    has been convicted twice, if the convictions arise from separate occasions:

1.    under subsection (a) of this section or § 5–609 of this subtitle;

2.    of conspiracy to commit a crime included in subsection (a) of this section or § 5–609 of this subtitle;

3.    of a crime under the laws of another state or the United States that would be a crime included in subsection (a) of this section or § 5–609 of this subtitle if committed in this State; or

4.    of any combination of these crimes.

(2)    A separate occasion is one in which the second or succeeding crime is committed after there has been a charging document filed for the preceding crime.

(d)    A person who is convicted under subsection (a) of this section or of conspiracy to commit a crime included in subsection (a) of this section is subject to imprisonment not exceeding 40 years or a fine not exceeding $25,000 or both if the person previously has served three or more separate terms of confinement as a result of three or more separate convictions:

(1)    under subsection (a) of this section or § 5–609 of this subtitle;

(2)    of conspiracy to commit a crime included in subsection (a) of this section or § 5–609 of this subtitle;

(3)    of a crime under the laws of another state or the United States that would be a crime included in subsection (a) of this section or § 5–609 of this subtitle if committed in this State; or

(4)    of any combination of these crimes.

(e)    A person convicted under subsection (a) of this section or of conspiracy to commit a crime included in subsection (a) of this section is not prohibited from participating in a drug treatment program under § 8–507 of the Health – General Article because of the length of the sentence.