In California, the responsibility for a motorcycle accident is determined based on the concept of negligence. Negligence refers to the failure to exercise reasonable care that a prudent person would have exercised in similar circumstances, resulting in harm or injury to another person. In motorcycle accidents, liability or responsibility for the accident is typically attributed to the party whose negligence directly caused or contributed to the accident. This could be the motorcyclist themselves, another driver involved in the accident, or even multiple parties if their actions or negligence led to the collision.