In California, there are laws that protect workers who work overtime. While there are some positions that are exempt from overtime laws and regulations, the majority of people working in the state are able to seek overtime if they work more than a 40-hour week. In general, the law states that no person, except the exempt, may work over 40 hours in one week without receiving 1.5 times the normal regular rate of pay for any hours over the traditional 40-hour workweek. Anyone who works more than 12 hours in one day should be paid double for hours extending past 12 and again for all hours that are worked in excess of eight on the seventh day of continual work.
There are several jobs and types of workers exempted from the law. For example, a salaried worker may not be entitled to overtime if they meet the exempt status that has been created by the state and federal laws. The Industrial Welfare Commission Wage Orders may also specifically exempt certain workers in various fields from overtime conditions.
Probably most interesting of the laws in California is the right for employers to ask employees to work more than 40 hours in one week. Employers have a right to schedule an employee's hours as and when necessary. If the employee refuses to work or does not show up during the overtime hours, then the employer may have the right to fire the employee.
If you're asked to work overtime and are not paid appropriately, your employer is violating the law. It's in your best interest to keep documentation so that you can present it to the courts.
Source: State of California Department of Industrial Relations, "Overtime," accessed July 14, 2017