Maryland Labor and Employment Section 3-211
§ 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.