The short answer is yes, your employer can require you to work overtime and can fire you if you refuse, according to the Fair Labor Standards Act (29 U.S.C. § 201) and according to the federal overtime law.
The Federal Labor Standard does not set a limit on how many hours a day or week your employer can require you to work. However, it does require only that employers pay employees overtime (time and a half the worker’s regular rate of pay) for any hours over 40 that the employee works in a week.
Please note that according to federal overtime law, your employer does not have to pay you overtime if you work more than eight hours in a day. The federal law is interested only in weeks, not days. As long as you work fewer than 40 hours in a week, you aren’t entitled to overtime. However in California, the law requires employers to pay workers overtime if you work more than eight hours per day.
David Payab, Esq. from The Law Offices of Payab & Associates can be reached @ (818) 918-5522 or by visiting http://payablaw.com/