What the law actually says
Assembly Bill 51 wrote lane splitting into the Vehicle Code (§21658.1) and authorized the California Motorcyclist Safety Program to publish safety guidance — speed differentials, when splitting is prudent, where it isn't. The guidance is advice, not law: exceeding it can feed a comparative-fault argument, but splitting itself is never the violation.
The crash that defines these cases
Hypothetically: a rider splits lawfully between stopped 210 lanes at a modest speed differential when a driver — frustrated, mid-text, or both — changes lanes into the gap. The driver's duty to check the lane before moving didn't vanish because the rider was between lanes. Fault in that scenario sits where it always sits: on the unsafe lane change.
How insurers fight it anyway
Three moves, every time: call splitting reckless (it's legal), inflate the rider's speed (prove it), and lean on juror bias (address it head-on). The counters are evidentiary — crush damage and scrape patterns establish relative speeds and lane positions, helmet-cam and dashcam footage settle everything, and the CHP guidance itself becomes YOUR exhibit when the riding was within it. The playbook against these tactics runs deeper in how insurers work rider claims.
What a splitting rider should do post-crash
Beyond the universal steps: preserve the bike and gear un-repaired until photographed, pull your own camera footage immediately, and decline every speed-estimate question from the other insurer — “the physical evidence will show speeds” is a complete answer. Then get the case read by someone fluent in rider claims — because comparative-fault percentages are where these cases are won, and they're negotiated, not decreed.
