When you get a subpoena, you’re in trouble. The term actually means “under punishment” in Latin. In essence, it is a court order to appear for a trial. Failure to appear can lead to fines and/or arrest, due to contempt of court. The UK equivalent of a subpoena is “witness summons.”
The subpoena document is prepared by the court clerk, after he or she has been given a list of witnesses by the attorneys. It is usually a form letter, which provides crucial data like the date and time of the testimony.
Your appearance is expected on that date and time even if the trial has been delayed. Only then will you be given another “appointment” with the court. This may mean having to wait for many hours, or worse, many days—though this is till preferable to the punishment for not showing up at all.
If there is a conflict of schedule, and the reason is very valid and serious, the attorney can negotiate with the court to change the date of the subpoena. It is also possible to provide the testimony in another location, like a hospital, or to give it over a long distance. However, it is necessary to court procedure that both the defense attorney and the prosecuting attorney be present in order to conduct examination and cross-examination.
Attorneys are the ones who decide who to subpoena, based on the case and the side they are defending. For example, a defense attorney will call any witness who can strengthen his case for the person’s innocence. The prosecuting attorney will look for witnesses that will prove guilt.
Following the subpoena orders is also crucial in child custody battles, since the court tends to be more compassionate towards the spouse that appears.