Does a defendant have an opportunity to "sift the conscience" of a witness?

defendant] has an opportunity, not only of testing the recollection and sifting the conscience of the witness, but of compelling him to stand face to face with the jury in order that they may look at him, and judge by his demeanor upon the stand and the manner in which he gives his testimony whether he is worthy of belief.' " [Citations.] To deny or significantly diminish this right deprives a defendant of the essential means of testing the credibility of the prosecution's witnesses, thus calling "into question the ultimate ' "integrity of the fact-finding process." ' " [Citation.]' [Citation.]" (People v. Herrera (2010) 49 Cal.4th 613, 620-621 (Herrera).)