California Formally Recognizes Lane Splitting

Governor Signs Bill Into Law

California has traditionally permitted lane splitting. However, state law neither prohibited nor specifically allowed the maneuver.

That all changed when Gov. Jerry Brown signed Assembly Bill 51, sponsored by Assembly members Bill Quirk and Tom Lackey. It authorized the California Highway Patrol to devise educational guidelines for splitting lanes “in a manner that would ensure the safety of the motorcyclist, drivers and passengers.”

The governor signed the bill on Aug. 19. It passed the Assembly 74-0 on Aug. 3, with six Assembly members not voting. The state Senate had earlier passed the bill 38-0.

A.B. 51 defines lane splitting as “driving a motorcycle that has two wheels in contact with the ground between rows of stopped or moving vehicles in the same lane.”

The bill, which was actively supported by the AMA, also requires the California Highway Patrol to consult with other agencies and organizations with an interest in road safety and motorcyclist behavior in developing the guidelines for responsible lane splitting.

Two state-sponsored studies conducted by the University of California Berkeley concluded that lane splitting is a relatively safe maneuver when both the motorcyclist and nearby drivers know the law and adhere to “safe and prudent” practices.

Lane-splitting riders were less likely to be rear-ended by another vehicle than were other motorcyclists, according to the studies. And lane-splitting motorcyclists involved in crashes were notably less likely than other motorcyclists to suffer head injuries, torso injuries or fatal injuries.

The studies also found that there was no meaningful increase in injuries until traffic speed exceeded 50 mph and that speed differentials between lane-splitting motorcyclists and other traffic were not associated with changes in injury occurrence until the differential exceeded 15 mph.

Those findings closely align with lane-splitting guidelines posted on the CHP website in 2013 and removed in 2014 after a complaint from a Sacramento resident, who argued that by posting the guidelines, the CHP was, in effect, making law.

The AMA supports lane splitting when done responsibly and legally. The AMA position statement on lane splitting can be read at