CA Gov't Code Section 4334

Public officers and bodies charged with the letting of contracts for public work, with the construction of public bridges, buildings and other structures, or with the purchase of supplies for any public use may give such contracts and purchase such supplies from persons manufacturing in the State the supplies to be used pursuant to contract or the supplies to be purchased if:

(a)

The bids of such persons, or the prices quoted by them, do not exceed by more than 5 per cent the lowest bids or prices quoted by persons manufacturing the supplies outside the State.

(b)

The major portion of the work of manufacturing the supplies is not done outside the State.

(c)

In the opinion of the public officers or bodies, the public good will be served thereby.