In the absence of an arrest, indictment or criminal charges filed, Federal Rule of Civil Procedure 45(c)(3)(B)(iii) states:
Rule 45. Subpoena
(c) PROTECTING A PERSON SUBJECT TO A SUBPOENA.
(3) Quashing or Modifying a Subpoena.
(B) When Permitted. To protect a person subject to or affected by a subpoena, the issuing court may, on motion, quash or modify the subpoena if it requires:
…
(iii) a person who is neither a party nor a party’s officer to incur substantial expense to travel more than 100 miles to attend trial.
Either I was asleep at the switch in the immediate aftermath of 9/11 or we now have a “rogue” Federal gubment on our hands. I suspect it was the former with influence from the latter.