What is an "at will" employee?

In California, there is a presumption that people are employed on an "at will" basis. That generally means that an employee may be terminated for any reason, so long as the termination is not based on a prohibited criteria such (for example) as race or sex discrimination. If an employee is working under a contract that spells out how and when a person may be terminated, then generally speaking the person can only be terminated for reasons specified in the contract. In California, the presumption of at-will employment can be refuted by evidence which demonstrates that the parties actually agreed that the employer's power to terminate is limited in some way. This is an area that is often disputed and often litigated. Consult with a knowedgeable employment law attorney if you have questions about terminating an employee.