Q: If a motorcycle lane splitting me on the left collides with me when making a left turn in a parking lot who is at fault?

A: If he was lane splitting on your left, then there must have been another lane of travel to your left. In which case, you were turning left across a lane of travel. The left turn statute requires you to yield to oncoming traffic, which doesn't apply. (http://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=21801.).

Vehicle Code section 22100(b) requires that you make a left turn from "as close as practicable to the left-hand edge of the extreme left-hand lane or portion of the roadway lawfully available to traffic moving in the direction of travel of the vehicle . . ." (https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=22100). You apparently were not in the property lane to make a left hand turn and were at least partially at fault for the collision. Whether the motorcyclist should have seen your turn signal and appreciated that you intended to turn left unlawfully might place some fault on him as well.

A: It's hard to tell if you were turning into a parking lot, or were already in a parking lot. The Vehicle Code doesn't really apply to a parking lot since it is not a road or highway. Nevertheless, I believe that a jury would tend to apply the same rules of the road.

A: The answer is fact-specific and it is unclear to me how the incident occurred. Generally speaking, it is negligent to operate your vehicle in an unsafe manner so if you are making a turn when it is unsafe to do so, you may be found to be at-fault. If the other driver is making a claim against you, you should tender it to your insurance company.