A: A preliminary hearing can be one of the most crucial hearings in your case. The preliminary hearing is not a trial. The main purpose of a preliminary hearing is to protect your right against an unlawful arrest and detention. At this hearing the Commonwealth must make at least a prima facie case - that is, at least a minimal showing - that a particular crime was committed and that you are probably the one who committed it. At this stage, the Commonwealth doesn't have to prove your guilt beyond a reasonable doubt. In order to meet its burden the Commonwealth must present some evidence regarding each of the material elements of the crime charged If the government can't meet this burden, your case will be dismissed.