California is the only state where lane-splitting (or filtering) is legal. By legal, I mean that it is permitted, but there are no official laws regarding the practice:
California law does not allow or prohibit motorcycles from passing other vehicles proceeding in the same direction within the same lane, a practice often called “lane splitting,” “lane sharing” or “filtering.” (DMV.ca.gov)
Lane-slitting is when a motorcyclist rides between two lanes of traffic moving in the same direction in order to avoid being rear-ended, which accounts for about a quarter of all accidents involving a motorcycle and car.
The debate between both motorcyclists and motorists who oppose the practice and those that support it has been ongoing for years now. Studies and statistics aside, bikers have been slitting lanes in California for decades and most of those who share the road with them are likely not even aware of the ambiguity surrounding its legality.
A bill was put forth last year (AB 51) attempting to put guidelines on the practice, thus making it legal with certain restrictions. AB 51 was authored by Assemblyman Dan Quirk (D-Hayward) and included guidelines such as speed limits while lane-splitting (motorcyclists could go no faster than 15 MPH above the moving traffic and no faster than 50 MPH overall). A two-year study on lane-splitting by UC Berkeley concluded that riders who employed the practice were safer than those who sat in place in traffic, thus increasing their vulnerability to be hit from behind. AB51 has been put aside for now so supporters can have more time to work on the measure.
There are car drivers who intensely dislike lane-splitting and even some who go out of their way to inhibit it by blocking the motorcyclist’s way or, incredibly, opening car doors on them. While this is not the norm, it is of note here because of the amount of tourists California has on the road at any given time. Riders who rent motorcycles here in California should bear in mind that although the practice of lane-splitting is not new, it is still disliked by many local drivers who view it as an unsafe and unfair way for motorcyclists to avoid traffic. In addition, there is also danger from out-of-state drivers who might not be aware of lane-splitting.
If you have questions or concerns about lane-splitting, be sure to talk to the guys at OC Motorcycle when you rent your bike and route your trip. Vigilance is the key when riding a motorcycle and if you are new to riding or not familiar with California driving and traffic patterns, lane-splitting should be avoided.