However, I have had two cases recently where the prosecutor wanted enhanced penalties for a DUI with priors outside of the ten year statutory period. One of these cases was a DUI in Santa Ana, Orange County, which is a notoriously difficult court for Orange County DUI lawyers. The Prosecutor wanted forty five days county jail for a defendant on a DUI because he had two prior DUI convictions which were more than ten years old. Forty five days in county jail is more than some defendants get for a second DUI within the statutory period, even in Santa Ana. The other case involved a borderline blood alcohol reading with facts justifying a dismissal or reduction in charges. The Prosecutor hesitated to offer a reduction because of a prior DUI which was about fifteen years old.

Call me old fashioned, but if the legislature states that prior convictions should make a difference to penalties if they are less than ten years old, shouldn't we assume that the legislature also meant that a person starts with a clean slate if they remain offense free for ten years?

Most people believe that after ten years prior convictions are removed from their record. This is not the case at all and old convictions can be viewed on a DMV record many years later. 

At least (for now) the DMV play by the rules and disregard old priors outside of ten years for the purposes of the length of any APS suspension. 

It appears therefore, that depending on the prosecutor or judge, a prior conviction for DUI can come back to haunt a defendant many years after it has reached its ten year anniversary.