Any offense which would otherwise be an infraction is a misdemeanor if a defendant has been convicted of three or more violations of this code or any local ordinance adopted pursuant to this code within the 12-month period immediately preceding the commission of the offense and such prior convictions are admitted by the defendant or alleged in the accusatory pleading. For this purpose, a bail forfeiture shall be deemed to be a conviction of the offense charged.
This section shall have no application to violations by pedestrians.
Source:
Section 40000.28, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=40000.28..