CA Gov't Code Section 19818.8

(a)

A person shall not be assigned to perform the duties of any class other than that to which his or her position is allocated, except as permitted by Section 19050.8.

(b)

If the provisions of this section are in conflict with the provisions of a memorandum of understanding reached pursuant to Section 3517.5, the memorandum of understanding shall be controlling without further legislative action, except that if those provisions of the memorandum of understanding require the expenditure of funds, the provisions shall not become effective unless approved by the Legislature in the annual Budget Act.