Unfortunately, the letter rogatory is needed. I assume the witness just won't appear voluntarily?
To questioners from West Virginia & New York: Although I am licensed to practice in your state, I practice on a day-to-day basis in Massachusetts. I answer questions in your state in areas of the law in which I practice, and in which I feel comfortable trying to offer you assistance based on my knowledge of specific statutes in your state and/or general principles applicable in all states. It is always best, however, to work with attorneys and court personnel in your own area to deal with specific problems and factual situations.
A subpoena is an order issued by counsel under counsel's authority as officer of the court to compel a witness to show up and give testimony and/or produce documents. However, a court of one state has no jurisdiction over a nonparty domiciliary of another state. I.e., imagine you get a subpoena from a lawyer in South Dakota. Why would that court have any jurisdiction to order you to do anything? You'd just laugh if you received it!
An order from thenonparty witness's state of domicile is necessary. For that one needs leters rogatory from the state where the action is pending. Probably the nonparty witness's home state will not compel the witness to travel out of state, only to sit for deposition in the home state.
General principles, not legal advice. Contact counsel in Massachusetts and New Hampshire to obtain legal advice. I practice in Vermont ONLY.
You need to file a request for a commission or letter rogatory which is essentially a request from the MA court to the NH court that includes a copy of the subpoena you want issued. Then you or a local NH-licensed attorney must file an ancillary action in NH asking that jurisdiction to issue an order subpoena-ing the witness to appear in the MA court on xx date and xx time to testify. Its not as complicated and drawn out as it might seem but you should grt moving on it nowif you need this witness for an upcoming trial.
This response is not to be considered legal advice by anyone. This communication, alone, does not create an attorney-client privilege. Unless you have executed a fee agreement with the attorney, that is related to the subject matter contained in this communication, you are advised not to rely on this communication to make any decisions whatsoever or to create an attorney-client relationship. No attorney-client relationship shall exist with this attorney without a fee agreement executed by you and the attorney.