Cal. Pub. Util. Code § 130350

A retail transactions and use tax ordinance applicable in the incorporated and unincorporated territory of the County of Los Angeles may be adopted by the Los Angeles County Transportation Commission in accordance with Part 1.6 (commencing with Section 7251) of Division 2 of the Revenue and Taxation Code, provided that two-thirds of the electors voting on the measure vote to authorize its enactment at a special election called for that purpose by the commission.