Myth No. 6: I have to file a copy of the subpoena before it is binding on the witness.
Until I started writing this article, I thought that was the rule. All the prosecutors with whom I have litigated file subpoenas for officers and witnesses in the courthouse as a rule. If a witness does not show for court, the judges first check the file to see if a copy of the subpoena is there before issuing a warrant for the witness or resetting the case. Notwithstanding all of this local practice, there is no authority anywhere that says the subpoena has to be filed to be binding. All that RCr 7.02(4) requires for proof of service is an affidavit endorsed upon the subpoena by the person serving the subpoena. While interests of judicial expediency would be accommodated if the copy of the subpoena were already in the file, the rule seems to allow counsel to produce proof of service from his or her own file at the time of trial, when a witness does not show.
Most of the time, especially when the witnesses are already known to the Commonwealth, counsel would want to file the subpoenas to avoid losing them, or having to make an argument why they do not have to be filed. However, sometimes there is that “surprise” witness that the Commonwealth does not know about, and filing the subpoena would threaten to spoil that surprise. In that instance, it might be best to not file the subpoena, and take your chances that if the witness is a no-show, the judge will not force you to trial for failure to file the proof of service.
an excerpt from The Subpoena: Ethical Use and Unethical Myth-Use by Scott West