Under Federal Law, for most jobs there is no limit in the amount of hours an employer can command you to work. However, there are very strict laws regarding compensation and unless you are properly an exempt employee you should be receiving time and a half for any hours in excess of 40. Also, certain state laws dictate what type of breaks you should be receiving and whether they are paid or not. You should speak with a wage and hour lawyer that offers free consultations to go over your compensation structure to make sure you are not being shorted.
Jason T. Brown
Please note by answering this question there is no attorney-client relationship formed. I am not your attorney. Nothing I said in this reply can or should be relied on. In order to rely on counsel's advise you must retain that attorney and receive representation or an official opinion letter. This is neither and meant to be for general informational purposes. Your case has specific nuances that goes beyond what you wrote and what I answered and you must speak directly with counsel to advise you of your rights. Please note I am only giving advice in the jurisdictions I am admitted (NJ, NY, PA). In any other jurisdiction I am discussing the law in general from an academic sense and not state specific rights. You should consult with a lawyer in your local jurisdiction.