Cal. Const. art. XIX, § 4

(a) Except as provided in subdivision (b), the statutory formulas in effect on June 30, 2009, which allocate the revenues described in Section 2 to cities, counties, and areas of the State shall remain in effect.
(b) The Legislature shall not modify the statutory allocations in effect on June 30, 2009, unless and until both of the following have occurred:
1. (1) The Legislature determines in accordance with this subdivision that another basis for an equitable, geographical, and jurisdictional distribution exists. Any future statutory revisions shall (A) provide for the allocation of these revenues, together with other similar revenues, in a manner which gives equal consideration to the transportation needs of all areas of the State and all segments of the population; and (B) be consistent with the orderly achievement of the adopted local, regional, and statewide goals for ground transportation in local general plans, regional transportation plans, and the California Transportation Plan;
2. (2) The process described in subdivision (c) has been completed.
(c) The Legislature shall not modify the statutory allocation pursuant to subdivision (b) until all of the following have occurred:
1. (1) The California Transportation Commission has held no less than four public hearings in different parts of the State to receive public input about the local and regional goals for ground transportation in that part of the State;
2. (2) The California Transportation Commission has published a report describing the input received at the public hearings and how the modification to the statutory allocation is consistent with the orderly achievement of local, regional, and statewide goals for ground transportation in local general plans, regional transportation plans, and the California Transportation Plan; and
3. (3) Ninety days have passed since the publication of the report by the California Transportation Commission.
(d) A statute enacted by the Legislature modifying the statutory allocations must be by a bill passed in each house of the Legislature by rollcall vote entered in the journal, two-thirds of the membership concurring, provided that the bill does not contain any other unrelated provision.
(e) The revenues allocated by statute to cities, counties, and areas of the State pursuant to this article may be used solely by the entity to which they are allocated, and solely for the purposes described in Sections 2, 5, or 6 of this article.
(f) The Legislature may not take any action which permanently or temporarily does any of the following: (1) changes the status of the Highway Users Tax Account as a trust fund; (2) borrows, diverts, or appropriates these revenues for purposes other than those described in subdivision (e); or (3) delays, defers, suspends, or otherwise interrupts the payment, allocation, distribution, disbursal, or transfer of revenues from taxes described in Section 2 to cities, counties, and areas of the State pursuant to the procedures in effect on June 30, 2009.