Legal Question in Criminal Law in California

Not clear what you mean by "expunged." If you didn't do actual state prison time, the usual method is a motion to reduce to a misdemeanor followed by a 1203.4. If you did, you wait 5 years after you're off parole and apply for a certificate of pardon and rehabilitation. Unless you are applying for a government job, do not check the box. Maybe by the time they find out, if they find out, they will have hired you and seen what a good employee you are.

It depends on what job you are applying for. Government jobs, as pointed out by Mr. Stone, always require disclosure of convictions, whether they were expunged or not. But this is broader than just working for a government agency. That also includes license applications for professions regulated by the State, such as teachers, accountants, lawyers, etc.

Many felony and misdemeanor convictions [not infractions] can sometimes be 'expunged'. If successful, the conviction would be retroactively withdrawn and the charges dismissed. That does not 'remove' the conviction, but merely changes the record to show 'conviction reversed and dismissed by expungement'. If expunged, you would be able to say 'no' to conviction on most private employment applications. However, the conviction is still a 'prior' for purposes of repeat offense, and must be disclosed on any application for government and professional licensing and employment, bonding, security clearance, etc. The agency and employer then can decide whether you are barred from employment because of your conviction.