Section 100C. In any criminal case wherein the defendant has been found not guilty by the court or jury, or a no bill has been returned by the grand jury, or a finding of no probable cause has been made by the court, the commissioner of probation shall seal said court appearance and disposition recorded in his files and the clerk and the probation officers of the courts in which the proceedings occurred or were initiated shall likewise seal the records of the proceedings in their files. The provisions of this paragraph shall not apply if the defendant makes a written request to the commissioner not to seal the records of the proceedings.

In any criminal case wherein a nolle prosequi has been entered, or a dismissal has been entered by the court, and it appears to the court that substantial justice would best be served, the court shall direct the clerk to seal the records of the proceedings in his files. The clerk shall forthwith notify the commissioner of probation and the probation officer of the courts in which the proceedings occurred or were initiated who shall likewise seal the records of the proceedings in their files.

Such sealed records shall not operate to disqualify a person in any examination, appointment or application for public employment in the service of the commonwealth or of any political subdivision thereof.

An application used to screen applicants for employment, housing or an occupational or professional license which seeks information concerning prior arrests or convictions of the applicant shall include in addition to the statement required under section one hundred A the following statement: ''An applicant for employment, housing or an occupational or professional license with a sealed record on file with the commissioner of probation may answer 'no record' with respect to an inquiry herein relative to prior arrests or criminal court appearances.'' The attorney general may enforce the provisions of this section by a suit in equity commenced in the superior court.

The commissioner or the clerk of courts in any district or superior court or the Boston municipal court, in response to inquiries by authorized persons other than any law enforcement agency or any court, shall in the case of a sealed record report that no record exists. After a finding or verdict of guilty on a subsequent offense such sealed record shall be made available to the probation officer and the same, with the exception of a not guilty, a no bill, or a no probable cause, shall be made available to the court.