(a) Opinion and reputation evidence of character. The credibility of
a witness may be attacked or supported by evidence in the form of
opinion or reputation, but subject to these limitations:
(1) The evidence may refer only to character for truthfulness or
untruthfulness, and
(2) Evidence of truthful character is admissible only after the
character of the witness for truthfulness has been attacked by opinion
or reputation evidence or otherwise.
(b) Specific instances of conduct. Specific instances of the conduct
of a witness, for the purpose of attacking or supporting the witness'
credibility, other than conviction of crime as provided in Sec. 18.609,
may not be proved by extrinsic evidence. They may, however, in the
discretion of the judge, if probative of truthfulness or untruthfulness,
be inquired into on cross-examination of the witness, concerning the
witness' character for truthfulness or untruthfulness, or concerning the
character for truthfulness or untruthfulness of another witness as to
which character the witness being cross-examined has testified.
The giving of testimony by any witness does not operate as a waiver
of the witness' privilege against self-incrimination when examined with
respect to matters which relate only to credibility.