Md. Code, Labor and Employment § 3-211

(a) (1) Except as provided in subsection (b) of this section, a minor under the age of 16 years may not be employed or allowed to be employed:

(i) before 7:00 a.m.;

(ii) from the day after Labor Day through the day before Memorial Day, after 8:00 p.m.;

(iii) from Memorial Day through Labor Day, after 9:00 p.m.; or

(iv) more than:

1. 4 hours on a day when school is in session;

2. 8 hours on a day when school is not in session;

3. 23 hours in a week when school is in session for 5 days; or

4. 40 hours in a week when school is not in session.

(2) The hours of work allowed under paragraph (1)(iv) of this subsection do not include any hours that a minor works in a bona fide work-study or student-learner program while school normally is in session.

(b) The Commissioner may grant to a minor an exception to the restrictions under this section if the Commissioner:

(1) receives the written consent of a parent of the minor or a person standing in the place of the parent; and

(2) determines that:

(i) there will be no hazard to the health or welfare of the minor; and

(ii) granting the exception will not impede the minor in fulfilling school graduation requirements.