Because California is an at-will employment state, there are no specific laws that protect employees if they call in sick. This means that an employee can be fired at any time, even if he called in for a legitimate illness.
However, there is the California Family Rights Act, which gives eligible employees the option to take a leave from work based on specific circumstances related to medical conditions. Under this act, an employee is able to return to work, either to his same job or a job of equal standing. Employees can take up to 12 weeks of leave for qualifying conditions.