I have split lanes many times while living in California.

There is no law in California that allows lane splitting. It is allowed because there is no law specifically forbidding lane sharing. Technically, you can get a ticket for excessive lane changes if you are weaving back and forth between two lanes. I remember passing two police cars one day, and the officer in the back car, started yelling at me about it. I slowed down when passing the lead car and asked if I was doing something illegal. He said, not to worry about it, the other officer was always trying to scare motorcyclists out of the habit.

I would never lane split if the cars were moving more than about 10-15 MPH. And I never drove faster than about 25 while doing it. Some cage drivers would be offended, but most were tolerant of the practice and realized that there is no reason not to take advantage of the smaller dimensions of a bike.

Like everyone, I think it's just plain crazy to lane split at high speeds. You never know when a cage is going to change lanes.

Ride safe.

Putz