In almost every state, an employee is considered to be "at will" unless there is a specific agreement to the contrary. This means that the employment relationship exists only as long as both parties want it to, and an employee can quit or be fired at any time, for any reason or no reason at all. If there is a dispute as to this status, it is up to the employee to prove in court that she was not an at-will employee, based on the written or oral statements of the employer. This can happen if an employer gives an at-will employee a reasonable impression that their position is guaranteed for a period of time, or that they can only be fired for good cause.