If you have an employment contract or agreement guarantying your title, level, opportunities, salary, etc., that agreement may be enforced.If you do not have such an agreement or contract, however, you are an employee at will. An employee at will may be demoted, transferred, have duties or title changed, pay reduced, etc.--or even be terminated entirely--at any time, for any reason, including simply that the employer wants to do any of these things. Thus, if you are an employee at will, your employer  "thinking" that a position will not work out for some reason--any reason--is enough for a demotion. Also, employers don't have to be consistent or fair in how they treat staff, with one exception: it is illegal to discriminate on the basis of a person's race, religion, age over 40, disability, or sex.