Two DUI cases pending in different California counties do not merge into one case; each county’s court and prosecutor handles its own case, and nothing combines them automatically. They affect each other through the repeat-offense rules. Once either case ends in a conviction, the prosecutor in the other county can charge that conviction as a prior, because the rule asks whether your offense occurred within 10 years of a separate DUI violation that resulted in a conviction, not which arrest came first.
Why the order of the arrests does not matter
California’s multi-DUI sentencing laws apply the enhanced penalty when the offense you are being sentenced for occurred within 10 years of a separate violation that resulted in a conviction (Vehicle Code section 23540). Two things follow. The 10 years is measured between the offenses themselves, and the other case counts only once it has actually produced a conviction. A charge that is still pending in the other county is not yet a prior.
The separate violation can come before or after the offense in your current case. Interpreting the same “separate violation” wording in an earlier version of the law, the California Supreme Court concluded that the Legislature intended repeat DUI offenders to face enhanced penalties “regardless of the order in which the offenses were committed and the convictions obtained” (People v. Snook (1997) 16 Cal.4th 1210). The court explained that the Legislature chose that wording so the timing of court proceedings would not let someone escape the repeat-offense penalties. In practice, whichever of your two cases ends in a conviction first can be charged as a prior in the case that is still open, even if the open case involves the earlier arrest.
It must be charged and proved, not assumed
The other county’s conviction does not attach to your case automatically. It must be specifically charged in the accusatory pleading, where you are asked whether you admit or deny having suffered it (Penal Code section 1025(a)). If you deny it, the prosecution has the burden of proving the alleged conviction beyond a reasonable doubt before it can be used against you (CALCRIM No. 2125). Courts do look for it: in every DUI case, the court must obtain your DMV driving record to check for separate DUI convictions within 10 years of the charged offense (Vehicle Code section 23622(b)), so a conviction entered in the other county can come to light that way.
Each county still runs its own case
Each county’s court, prosecutor, and case file moves on its own schedule, with its own plea negotiations and its own trial date. If you have two open cases, tell your attorney about both immediately so that plea timing and any agreement in one county can be weighed against what is happening in the other. Because the cases are independent, a plea in one case can create a conviction the other county is able to use, sometimes in ways that are not obvious until both cases are looked at together.
What this does not do for you
Trying to delay one case to outrun the other’s conviction is not a reliable strategy. Snook read the law specifically so that the order of court proceedings would not decide who faces the repeat-offense penalties, so scheduling maneuvers should not be counted on to avoid an enhancement. For background on what counts as a prior and how the penalties escalate, see second-time DUI defense and third DUI in California. If a new arrest happens while you are still on probation for an earlier DUI, that can raise a separate probation issue; see DUI probation violation.
If you have DUI cases open in two different California counties, the Law Offices of David S. Chesley can look at both cases together and explain how they affect each other. Call (800) 755-5174 to discuss your situation.