Cal. Vehicle Code § 21460.5

(a) The Department of Transportation and local authorities in their respective jurisdictions may designate a two-way left-turn lane on a highway. A two-way left-turn lane is a lane near the center of the highway set aside for use by vehicles making left turns in both directions from or into the highway. (b) Two-way left-turn lanes shall be designated by distinctive roadway markings consisting of parallel double yellow lines, interior line dashed and exterior line solid, on each side of the lane. The Department of Transportation may determine and prescribe standards and specifications governing length, width, and positioning of the distinctive pavement markings. All pavement markings designating a two-way left-turn lane shall conform to the Department of Transportation’s standards and specifications. (c) A vehicle shall not be driven in a designated two-way left-turn lane except when preparing for or making a left turn from or into a highway or when preparing for or making a U-turn when otherwise permitted by law, and shall not be driven in that lane for more than 200 feet while preparing for and making the turn or while preparing to merge into the adjacent lanes of travel. A left turn or U-turn shall not be made from any other lane where a two-way left-turn lane has been designated. (d) This section does not prohibit driving across a two-way left-turn lane. (e) Raised pavement markers may be used to simulate the painted lines described in this section when those markers are placed in accordance with standards established by the Department of Transportation.