What is the effect of the CALJIC 2.11.5 instruction on the prosecution's failure to jointly prosecute all those shown by the evidence to have been involved?

The purpose of CALJIC 2.11.5 is to discourage the jury from speculating about the prosecution's reasons for not jointly prosecuting all those shown by the evidence to have participated in the charged offenses, and to discourage speculation about the fates of unknown perpetrators. People v. Price, 1 Cal. 4th 324, 446 (1991). Under this rationale, the instruction should not be given if the "other person" who may have been involved testifies at trial, because it could prevent a jury from considering evidence of a co-participant's bias. Id. Another purpose for the instruction "is to focus the jury's attention on an individualized evaluation of the evidence against the person on trial without extraneous concern for the fate of other participants irrespective of their culpability." People v. Cox, 53 Cal. 3d 618, 668 (1991) (emphasis added, footnote omitted), disapproved on another ground in Doolin, 45 Cal. 4th at 421 n.22.

Page 143