Cal. Elections Code - ELEC § 15610. Section 15610.
If no election contest is pending wherein a recount of the ballots in a precinct has been or will be ordered, the elections official may order that the ballots voted in the precinct be publicly recounted if both of the following apply:
(a)
The elections official has reasonable cause to believe the ballots in the precinct have been miscounted.
(b)
The elections official has examined, under oath, the precinct board members or, in the case of ballots counted by a central counting system, the counting board members, and they are unable to explain the returns of their respective precincts.