Unfortunately, seniority doesn't automatically give an employee legal rights.  If you are an "at will" employee then, your employer can hire or fire you for any reason or no reason whatsoever, as well has increase/decrease salary/hours, promote/demote, and generally impose requirements as it sees fit.  An employee in turn can choose to work for an employer or not. Exceptions to this would be if there is a stated company policy that is contrary, or there is a union/employment agreement that does not allow for such action, or this situation has arisen due to some type of discrimination (i.e., for reasons due to your race, religion, age, disability, sex, national origin).