Section 343.5. Rules of evidence; impeachment of own witness by proof of prior contradictory statement

1. When, upon examination  by  the  party
  who  called  him,  a witness in a delinquency proceeding gives testimony
  upon a material issue of the case which tends to disprove  the  position
  of  such  party, such party may introduce evidence that such witness has
  previously made either a written statement signed  by  him  or  an  oral
  statement under oath contradictory to such testimony.
    2.  Evidence  concerning  a  prior  contradictory statement introduced
  pursuant to subdivision one may be received  only  for  the  purpose  of
  impeaching  the credibility of the witness with respect to his testimony
  upon the subject, and does not constitute evidence in chief.
    3. When  a  witness  has  made  a  prior  signed  or  sworn  statement
  contradictory  to  his  testimony  in  a  delinquency  proceeding upon a
  material issue of the case, but his testimony does not tend to  disprove
  the  position  of  the party who called him and elicited such testimony,
  evidence that the witness made such prior statement is  not  admissible,
  and  such  party  may  not  use  such prior statement for the purpose of
  refreshing the recollection of the witness in a  manner  that  discloses
  its contents to the court.