Thank you for your reply. I asked about the issue of why you might be the target of his behavior to see if perhaps you might have a legal issue versus a management issue. For this to be a legal issue, this employee would have to be targeting you because of your gender, race, national origin, religion, age (over 40), disability, pregnancy or military service. In that case, if you filed a discrimination complaint with the employer and they failed to resolve the issue, you could file a discrimination complaint with the State or the EEOC.
If this is a professional jealousy issue or a general unprofessional behavior, you would be limited by the procedures your employer has for filing complaints. In other words, this would be something you would have to try to resolve through management and not under the jurisdiction of the courts. Massachusetts is an employment "at will" state, so unless there is job or position protection by a contract, the employer could change any term or condition of employment, discipline and terminate as they deem appropriate, unless there is a discrimination issue I discussed earlier.
Please feel free to ask follow up questions if you have them. If none, then if you could take a moment to leave a positive rating in the box above, I will receive credit for assisting you today. Thank you