Md. Code, Transportation § 21–1112.1

(a) A person may not obscure or modify any vehicle registration plate in a manner that may prevent identification.

(b) A violation of this section is a moving violation for the purpose of the assessment of points under § 16–402 of this article.

(c) A police officer may enforce this section only as a secondary action when the police officer detains a driver of a motor vehicle for a suspected violation of another provision of the Code.