§ 768 Attendance of witness enforced, how.

If you need someone to testify as a witness, the court or magistrate can make sure they show up by issuing a subpoena. This is an official order that legally requires the person to appear, either at a hearing before a magistrate or at the actual trial.

A subpoena can come from two places. The magistrate who is holding the preliminary examination can issue one, or the court where the trial itself will happen can issue one. Either way, once a witness receives a subpoena, they are required by law to attend and testify. This gives both sides in a criminal case a way to get witnesses to court, even if the witness doesn't want to come on their own.