All cases under this chapter shall be heard at a special or separate session of the court, and no other matter shall be heard at such a session. No person on trial, awaiting trial, or under accusation of crime, other than a parent, guardian, or relative of the minor, shall be permitted to be present at any such session, except as a witness.

Cases in which the minor is detained and the sole allegation is that the minor is a person described in Section 300 shall be granted precedence on the calendar of the court for the day on which the case is set for hearing.