State-by-state guide:

Michigan

Mich. Comp. Laws § 712A.17(7) (1998): The public may be excluded from hearings upon a motion by any party, or by the victim, if the court finds it necessary to protect the welfare of a child witness or victim. In determining whether closing a hearing is necessary to protect the welfare of the juvenile witness or the victim, the court must consider the age of the juvenile witness or the victim, the nature of the proceeding and the desire of the juvenile witness, the witness’s family or guardian, or of the victim to have the testimony taken in a room closed to the public.

Mich. Comp. Laws § 712A.28 (1998): All case records are open to the general public, except for records of hearings which were closed. Those records can be opened by court order but only to persons having a legitimate interest.

Mich. Ct. R. 5.925 (1998) (incorporates above statutes): In general, juvenile hearings shall be open to the public. However, the court, on motion of a party or a victim, may close the proceedings to the public during the testimony of a child or during the testimony of the victim to protect the welfare of either. In making such a determination, the court shall consider the nature of the proceedings, the age and maturity of the witness and the preference of the witness, and the preference of a parent if the witness is a child, that the proceedings be open or closed. The court may not close the proceedings to the public during the testimony of the juvenile. Furthermore, records of the juvenile court other than confidential files shall be open to the general public. Only persons who are found by the court to have a legitimate interest may be allowed access to the confidential files. In determining whether a person has a legitimate interest, the court shall consider the nature of the proceedings, the welfare and safety of the public, and the interest of the minor. In addition, the court may at any time for good cause expunge its own files and records pertaining to an offense by or against a minor. The court must expunge the record of a juvenile within 28 days after the juvenile becomes 17 years of age. The court must expunge the files and records pertaining to a person’s juvenile offenses when the person becomes 30 years of age. With regard to child protective files and records, the court shall expunge such files and records 25 years after the jurisdiction over the last child in the family ends.