Legal Question in Business Law in Maryland

Unfortunately you have no right to your job because MD, like most states, adheres to the doctrine of "employment at will". This means that, with few exceptions (like civil rights violations), employers have an absolute right to discharge employees. So you will have to decide what is more important--doing your school work or the job. You might consider being proactive and approaching the manager and try and work something out that accommodates both. If that doesn't work, there may be other jobs out there that don't have the same minimum hours requirements.