§ 964 Officer may be directed to produce prisoner.

If a defendant is being held in jail or prison, the judge can order the officer holding that person to bring them to court so the judge can sentence them. Once the judge gives this order, the officer is required to follow it and bring the defendant to court.

This rule makes sure that someone in custody can still be brought before the court for sentencing. The defendant doesn't need to arrange this themselves. The responsibility falls on the officer or facility holding them to get them to court when the judge asks for it.