Md. Code, General Provisions § 4–308

(a) Subject to subsection (b) of this section, a custodian shall prohibit inspection, use, or disclosure of a circulation record of a public library or any other item, collection, or grouping of information about an individual that:

(1) is maintained by a library;

(2) contains an individual’s name or the identifying number, symbol, or other identifying particular assigned to the individual; and

(3) identifies the use a patron makes of that library’s materials, services, or facilities.

(b) A custodian shall allow inspection, use, or disclosure of a circulation record of a public library only:

(1) in connection with the library’s ordinary business; and

(2) for the purposes for which the record was created.