How Liability Is Determined

Liability in rear-end collision claims revolves around negligence—failing to act with reasonable care. The rear driver is typically presumed at fault, but this can be challenged with evidence.

Presumption of Fault

If you rear-end someone, California law assumes you weren’t driving safely—maybe you were too close or not paying attention. However, you can argue against this if the front driver did something reckless, like slamming on the brakes without reason or having broken tail lights.

In most cases, the rear driver is presumed to be at fault due to California Vehicle Code § 21703, which states: “The driver of a motor vehicle shall not follow another vehicle more closely than is reasonable and prudent…” 

However, there are exceptions where the lead driver may share or take full responsibility.

Comparative Negligence in California

California uses a pure comparative negligence system. This means fault can be split between both drivers, and even if you’re partly to blame, you can still recover damages—just reduced by your share of fault. For example, if you’re 30% responsible, you’d get 70% of your total damages. This rule is key in rear-end cases where both parties might share some responsibility (see California Civil Jury Instructions (CACI) No. 405). 

The court in Pfeifer v. John Crane, Inc. (2013) 220 Cal.App.4th 1270 held that “The comparative fault doctrine ‘is designed to permit the trier of fact to consider all relevant criteria in apportioning liability. The doctrine “is a flexible, commonsense concept, under which a jury properly may consider and evaluate the relative responsibility of various parties for an injury (whether their responsibility for the injury rests on negligence, strict liability, or other theories of responsibility), in order to arrive at an “equitable apportionment or allocation of loss.'” (Internal citations omitted). 

Insights from California Case Law

The following seminal cases in California review the inference of negligence or presumption in rear-end accidents and how that presumption may be rebutted. 

• Maloney v. Rath, 69 Cal.2d 442 (1968): The court in this case held that vehicle owners have a nondelegable duty to maintain their vehicles in a safe condition. The court held that even if a driver was unaware of a brake defect and had recently had their brakes serviced, they could still be held liable for a rear-end collision caused by brake failure. This decision reinforced the presumption of liability for rear drivers while limiting the effectiveness of the “sudden emergency” defense.
• Larson v. Solbakken, 221 Cal.App.2d 410 (1963): This California Court of Appeal case affirmed that in rear-end collisions there is a presumption negligence arises against the rear driver. However, the court clarified that this inference is rebuttable and does not require the defendant to prove they were not negligent by a preponderance of the evidence. Instead, it shifts the burden to the defendant to explain or justify their conduct.
• Kramer v. Barnes, 212 Cal.App.2d 440 (1963): In this seminal case, the Court of Appeals in California rules that the question of negligence in rear-end collisions is essentially one of fact and depends on the circumstances surrounding the accident. The court noted that when there is undisputed evidence of a rear-end collision, an inference of negligence arises. This case thus reinforces the law that the rear end driver may be presumed negligence in these types of accidents. 
• Davis v. Ewen, 148 Cal.App.2d 410 (1957): This case discussed how the presumption of rear driver liability can be rebutted in rear-end accidents in California. The court upheld a jury verdict in favor of the rear driver, finding that evidence of the lead vehicle’s sudden stop without warning, combined with the rear driver’s immediate application of brakes and inability to avoid collision, created a conflict in evidence that could reasonably be resolved in the rear driver’s favor.