Generally speaking, if a witness receives a subpoena, and if they fail to appear as requested, they could potentially be held in "contempt-of-court" with a bench warrant issued for their arrest. However, a warrant would only be issued if the subpoena was properly requested and entered pursuant to the applicable court-rules. If you need specific legal advice for your particular circumstances, I encourage you to privately consult with a lawyer.
Answered on Apr 18th, 2014 at 3:33 PM