California Motor Vehicle Code 21714
Motorcyclists or Motorized Bicyclists; Operation of Vehicle; Prohibited Areas
California Vehicle Code 21714 makes it illegal to ride on, or immediately adjacent to, markers designating lanes or between two or more vehicles traveling in adjacent lanes. This is often referred to as lane splitting.
Vehicle Code 21714 only applies to fully enclosed three-wheeled motorcycles and cars. If you're familiar with the Sparrows that were built in California from 2000-2002, then you've seen what the legislators had in mind when they enacted this rule.
Regular two-wheeled motorcycles are allowed to split lanes. California is one of the only states that allows for lane splitting on motorcycles. If you split lanes, remember that it is still incredibly unsafe, and most car and truck drivers don't know its legal and may try to cut you off.
Vehicle Code 21714 makes it illegal to split lanes in a three-wheeled motorcycles or cars because they are wider than two wheeled motorcycles. Because of their extra width, there is often not enough room between cars for a three-wheeled cycle to fit safely.
It is also illegal for these three-wheeled vehicles to operate in the HOV lanes, unless there are signs posted which specifically allow it. With the new technology being introduced with these vehicles, the law may change in the future. For now, however, stay out of the car pool lanes.
If you violate vehicle code section 21714, you will have points added to your license and receive fines. For your first offense, you could receive as much as $300 in penalties and court costs.