expungement of prior DUI convictions

DUI convictions can be expunged in California.  However, this is not done automatically.  You would have to make application to the court for each offense. 

The stature governing expungements is Section 1203; most DUI convictions come under section 1203.4  Technically, the expungement under this section is not an eraser of one's criminal record.  What is really happening is set out in the statute: the plea of guilty or no contest is being withdrawn and a plea of not guilty is being entered, or, if there was a trial, the verdict of guilty is being set aside.  In either case, the court is thereafter dismissing the charging document.  As noted in the statute, the probationer is, thereafter, "released from all penalties and disabilities resulting from the offense of which he or she has been convicted," with certain exceptions.

There is a split of opinion among those in the legal community about exactly what this means for those applying for a job and confronted with the question "have you ever been convicted of a crime?"  Since the statute says "released from all penalties and disabilities," subject only to those exceptions specifically set forth in the statute, the better reasoned view is that the legislature meant what it said, that "all penalties and disabilities" means just that, and if the legislature intended to say otherwise, they would have said so.  Therefore, once an order for relief pursuant to 1203.4 has been granted, the former-probationer can lawfully state that they have not been convicted of the crime when asked on a job application from a private (non-law enforcement) employer.

Those exceptions, where disclosure is required, are set out in the statute: "the order does not relieve him or her of the obligation to disclose the conviction in response to any direct question contained in any questionnaire or application for public office, for licensure by any state or local agency, or for contracting with the California State Lottery."  This means that if applying for public office, seeking any license from the state (real estate, stock broker, doctor, lawyer, etc.), or contracting with the California State Lottery, the conviction must be disclosed (although it can be disclosed as an expunged conviction).   While not mentioned in the statute, applications to become a Peace Officer typically require disclosure of expunged convictions.

It is also worth noting that in this day and age of computers, internet, and the free-flow of information, that a carefully worded disclosure may be the best way to proceed, even if disclosure is not required under the statute. 

You really should consult further with an attorney in your area.  For one thing, they can help you with applying for an expungement and for another they can counsel you on how to best handle disclosure issues.