I was discussing lane splitting with a co-worker, we disagreed what was legal, so I looked it up. Currently, California is the only state where splitting lanes isn’t against the law.

The CHP’s guidelines state that motorcyclists should only split the lane when traffic flows at 40 MPH or less.

 Also, they should not travel more than 10 MPH over surrounding traffic.

It seems, that the LAW isn't spelled out online, just the "CHP Guidelines" 

Section 21658.1 (a) was added to the California Vehicle Code. According to this law, lane splitting is defined “as 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.

(b) The Department of the California Highway Patrol may develop educational guidelines relating to lane splitting in a manner that would ensure the safety of the motorcyclist and the drivers and passengers of the surrounding vehicles.

I think, from what I read, that this is due to the governor, and the lawmakers, making a law that gave the CHP the priveldge of spelling out what they would ticket for, and not ticket for, as reckless and dangerous motorcycle behavior. 

https://cartwrightlaw.com/articles/motorcycle-lane-splitting-in-california-legal-but-misunderstood/

https://www.mesrianilaw.com/blog/is-lane-splitting-legal-in-california/