Given that in California a yellow light has no meaning other than as an indicator of a pending red light, a competent lawyer could argue that he has partial lia

Given that in California a yellow light has no meaning other than as an indicator of a pending red light, a competent lawyer could argue that he has partial liability in this case. The driver's handbook suggests stopping if it is safe to do so, otherwise proceeding with caution; but this is neither legally binding nor was it safe for him to stop by slamming on his brakes either time. But the legality of it is orthogonal to whether his behavior was right. It wasn't. It was unexpected, reckless, and very unsafe.