Request for Separate Trial In California
In People v. Sandoval (1992) 4 Cal.4th 155, 172 to 173, 841 P.2d 862, the Supreme Court explained the factors a trial court should consider in deciding a request for separate trials:
"'The determination of prejudice is necessarily dependent on the particular circumstances of each individual case, but certain criteria have emerged to provide guidance in ruling upon and reviewing a motion to sever trial.'
Refusal to sever may be an abuse of discretion where:
(1) evidence on the crimes to be jointly tried would not be cross-admissible in separate trials;
(2) certain of the charges are unusually likely to inflame the jury against the defendant;
(3) a 'weak' case has been joined with a 'strong' case, or with another 'weak' case, so that the 'spillover' effect of aggregate evidence on several charges might well alter the outcome of some or all of the charges; (4) any one of the charges carries the death penalty or joinder of them turns the matter into a capital case."
Of the Sandoval criteria only the first - the lack of cross-admissibility - supports severance.
However, cross-admissibility is not a necessary criterion for joinder. (See 954.1 "evidence concerning one offense . . . need not be admissible as to the other offense . . . before the jointly charged offenses may be tried together"; see Belton v. Superior Court (1993) 19 Cal.App.4th 1279, 1286 cross-admissibility no longer the primary factor for determining prejudice.)