Site: nolo.com
... In most states, the law presumes that employees are at will, unless they have a contract with their employer ... State law may allow the employer to fire employees only for cause, or the employee may have an employment ... However, unless a contract or law restricts the reasons for which the employer may terminate the employee ... But, the employer cannot legally fire anyone for a reason that breaches a contract or violates the law ... If the real reason for terminating an employee is discrimination, retaliation, employee whistle-blowing ...