Md. Code, Local Government § 20–601

(a) Except as provided in subsection (b) of this section, a county may impose

a sales or use tax on controlled dangerous substances as defined in § 5–101 of the

Criminal Law Article.

(b) A county may not impose a sales or use tax under subsection (a) of this

section on sales by a person who complies with Title 5, Subtitle 3 of the Criminal Law

Article.