California Code, Government Code - GOV § 11445.50

(a) The presiding officer may deny use of the informal hearing procedure, or may convert an informal hearing to a formal hearing after an informal hearing is commenced, if it appears to the presiding officer that cross-examination is necessary for proper determination of the matter and that the delay, burden, or complication due to allowing cross-examination in the informal hearing will be more than minimal.

(b) An agency, by regulation, may specify categories of cases in which cross-examination is deemed not necessary for proper determination of the matter under the informal hearing procedure. The presiding officer may allow cross-examination of witnesses in an informal hearing notwithstanding an agency regulation if it appears to the presiding officer that in the circumstances cross-examination is necessary for proper determination of the matter.

(c) The actions of the presiding officer under this section are not subject to judicial review.