US Title 28- Rule 45-e
(e) Contempt. The issuing court may hold in contempt a person who, having been served, fails without adequate excuse to obey the subpoena. A nonpartys failure to obey must be excused if the subpoena purports to require the nonparty to attend or produce at a place outside the limits of Rule 45 (c)(3)(A)(ii).
Contempt, sounds like at least a misdemeanor.