In California, it's common to see motorcycles driving over the lines between traffic. This practice is known as "lane splitting" and is allowed by California law under Vehicle Code 21658.1, which defines lane splitting as:
"Lane splitting" means driving a motorcycle, as defined in Section 400, that has two wheels in contact with the ground, between rows of stopped or moving vehicles in the same lane, including on both divided and undivided streets, roads, or highways.
The CHP, DMV, Department of Transportation, and the Office of Traffic and Safety are responsible for creating lane splitting rules and regulations. The statewide standard is that you may lane split so long as you do it safely without presenting a risk to yourself and others who share the road.
Many California drivers are unaware of the right to lane-split and sometimes provoke road rage incidents. Be mindful and practice lane splitting carefully. We recommend being vigilant of your surroundings and not driving faster than 10 miles per hour than the cars next to you.