Maryland Code, Transportation § 26-303

(a)(1) The person receiving a citation under this subtitle shall:

(2) An election to stand trial shall be made by sending a notice of intention to stand trial to the political subdivision or State agency at least 5 days before the payment date specified in the citation.

(b)(1) If a person elects to stand trial and desires the presence at trial of the officer who issued the citation, he shall so notify the political subdivision or State agency at the time the notice of intention to stand trial is given.

(2) If proper notification is not given, the officer need not appear at the trial, and the copy of the citation bearing the certification of the officer is prima facie evidence of the facts stated in it.