Most causation cases turn on whether the plaintiff can prove that this defendant caused the harm. Summers v. Tice is famous for the opposite move: it's the case where the plaintiff couldn't prove which defendant caused the injury—and won anyway. Two hunters, one injured eye, one pellet that could have come from either gun. The California Supreme Court decided that letting both negligent hunters off the hook because the plaintiff couldn't do the impossible would be a worse injustice than making them sort it out among themselves. That instinct—shift the burden onto the wrongdoers—is why this two-page opinion is in every Torts casebook.

What did Summers v. Tice hold?

In Summers v. Tice (Cal. 1948), the California Supreme Court held that when two or more defendants act negligently toward the plaintiff, and either one's conduct could have caused the injury, but the plaintiff cannot determine which defendant actually caused it, the burden of proof on causation shifts to each defendant to absolve himself. Because neither hunter could prove he was not the cause, both were held jointly and severally liable for the entire injury. This is the doctrine of alternative liability.

Case Summary

Summers v. Tice, 33 Cal. 2d 80, 199 P.2d 1 (1948), was decided by the Supreme Court of California. The plaintiff, Charles Summers, was shot in the eye and lip while on a quail-hunting trip with the two defendants, Tice and Simonson. Both defendants had negligently fired their shotguns in Summers's direction at the same time. The trial court, sitting without a jury, found both defendants liable, and the Supreme Court of California affirmed.

Facts

The three men were hunting quail. Summers was positioned roughly at the point of a triangle, with the two defendants forming the other two points. When a quail flushed and flew low between them, both Tice and Simonson fired their shotguns in Summers's direction—into the line of fire where they knew Summers was standing. Summers was struck by birdshot: one pellet lodged in his eye, another in his upper lip. The pellets were of the same size and came from identical guns. It was undisputed that only one of the two shots caused the eye injury (the serious harm), but it was impossible to determine which defendant fired the pellet that hit Summers's eye.

Procedural History

Summers sued both defendants. The trial court, without a jury, found that both defendants were negligent and that their negligence proximately caused the injury, entering judgment against both. The defendants appealed, arguing that the plaintiff had failed to prove which of them actually fired the injuring shot—a failure of the causation element that, they claimed, should defeat liability against both. The Supreme Court of California affirmed the judgment.

Issue

Where two defendants act negligently toward the plaintiff and either one could have caused the injury, but the plaintiff cannot prove which defendant's conduct was the actual cause, may both defendants nevertheless be held liable—or does the plaintiff's inability to identify the actual cause defeat the claim entirely?

Holding & Rule

Yes—both defendants may be held liable. The California Supreme Court held that once the plaintiff proves that each defendant acted negligently toward him and that one of them caused the injury, the burden of proof shifts to each defendant to prove that he did not cause the harm. If neither can meet that burden, both are jointly and severally liable for the full injury.

The outline-ready rule: When two or more defendants act tortiously toward the plaintiff, and it is proven that one of them caused the plaintiff's injury but the plaintiff cannot identify which, the burden shifts to each defendant to exonerate himself; a defendant who cannot do so is liable. This is alternative liability, later codified at Restatement (Second) of Torts § 433B(3).

Reasoning

The court's logic rested on fairness and the relative innocence of the parties. Both defendants were wrongdoers—each had negligently fired in the plaintiff's direction. Summers, by contrast, was entirely innocent. To deny recovery because Summers couldn't prove the one thing that was genuinely impossible for him to prove would let two negligent actors escape liability by hiding behind each other. As the court put it, the defendants "brought about a situation where the negligence of one of them injured the plaintiff, hence it should rest with them each to absolve himself if he can."

The court reasoned that the defendants were in a far better position than the plaintiff to know—or to offer evidence about—who fired the injuring shot. If anyone had access to that information, it was the shooters, not the victim. Shifting the burden to them was therefore both fair and practical.

The court also addressed the concern about holding a defendant liable who might in fact be innocent. It accepted that one defendant was, factually, not the cause—but concluded that as between two proven wrongdoers and one innocent plaintiff, the wrongdoers should bear the risk of indeterminacy. Joint and several liability then let Summers recover fully, leaving the defendants to sort out contribution between themselves.

Why Summers v. Tice Matters

Summers sits in the causation unit of Torts, right where your casebook is teaching "cause in fact" and the but-for test. Its job is to show you the doctrine's edge case: what happens when the but-for test breaks down because you genuinely cannot say which defendant was the but-for cause. Normally the plaintiff who can't prove causation loses. Summers is the narrow exception where the court reallocates that burden.

Doctrinally, it's the parent of one of the most-tested modern causation doctrines: market-share liability. When California later confronted DES cases in Sindell v. Abbott Laboratories (1980)—hundreds of manufacturers, no way to identify which made the drug that harmed the plaintiff—it reached back to Summers for the burden-shifting instinct, then modified it (because in DES cases you couldn't be sure all the tortfeasors were even in the courtroom). Understanding Summers is a prerequisite to understanding why Sindell had to invent something new.

Cold-Call Prep: The Questions Your Professor Will Ask

This is a burden-of-proof case, and professors love to press on exactly what shifts and why. Have these ready:

• "Why did the plaintiff win when he couldn't prove which defendant shot him?" — Because the court shifted the burden of causation to the defendants. Both were negligent, both fired at him, and only they had access to who caused the harm. As between two wrongdoers and an innocent plaintiff, the wrongdoers bear the risk of not being able to prove which one caused the injury.
• "What are the requirements for this rule to apply?" — (1) All possible tortfeasors are before the court; (2) each acted negligently/tortiously toward the plaintiff; (3) it's certain that one of them caused the injury; and (4) the plaintiff cannot identify which one. Watch that first requirement—it's what limits the doctrine.
• "Isn't the court holding an innocent defendant liable? One of them didn't cause the injury." — Yes, and the court accepted that. Its answer is a policy choice: between an innocent plaintiff and two proven wrongdoers, the wrongdoers should bear the loss and the uncertainty, especially since they're better positioned to produce evidence.
• "Who bears the burden after the shift, and what do they have to prove?" — Each defendant now must prove he was not the cause. If he can't, he's liable. The plaintiff no longer has to prove which one did it.
• "Why joint and several liability?" — So the fully innocent plaintiff recovers his entire damages from either defendant, and the defendants—not the victim—shoulder the problem of allocating the loss between themselves through contribution.
• "How is this different from res ipsa loquitur?" — This is a great trap question. Res ipsa is about inferring negligence from circumstances; Summers assumes negligence is proven and shifts the burden on causation. Don't conflate them.
• "What if there had been ten hunters and only two were before the court?" — The doctrine likely fails, because you can't say the injury-causer is definitely a defendant. This is the seam that Sindell and market-share liability were invented to fill.

On the Exam

Summers shows up in issue-spotters as a causation rescue. Your fact pattern gives you two (or a few) clearly negligent defendants, a single injury, and no way to tell which defendant's conduct caused it. The signal words: multiple negligent actors, indeterminate cause, closed set. When you see that, your causation analysis should flag that the but-for test fails as to any single defendant—and then you deploy Summers to shift the burden.

The trap: Students reach for Summers whenever causation is hard. It's not a general "I can't prove causation" escape hatch. Two requirements police it hard. First, every possible tortfeasor must be before the court—if the real culprit might be someone who isn't a defendant, the rule doesn't apply (that's the whole reason Sindell needed a different theory). Second, each defendant must have been tortious toward this plaintiff; you can't shift the burden onto someone who did nothing wrong. If your facts have three defendants but only two acted negligently, or if there's a real chance the injuring actor isn't in the courtroom, Summers doesn't fit—say so, and then pivot to whether market-share liability or ordinary causation analysis applies. Distinguishing Summers from where it doesn't apply is where the points live.

Also keep it clean from the concurrent-cause cases (like the two-fires problem in Kingston / Anderson). Those involve two sufficient causes that each actually contributed; Summers involves two possible causes where only one actually operated. Don't blur them.

Related Cases

• Sindell v. Abbott Laboratories (Cal. 1980) — Extends Summers's burden-shifting to DES manufacturers via market-share liability, precisely because the "all tortfeasors before the court" requirement couldn't be met.
• Ybarra v. Spangard (Cal. 1944) — A res ipsa / burden-shifting case involving an unconscious surgical patient and multiple defendants; often taught alongside Summers for its similar fairness-driven allocation.
• Kingston v. Chicago & N.W. Ry. / Anderson v. Minneapolis — The concurrent-cause "two fires" cases; contrast these (two sufficient causes) with Summers (two possible causes).
• Palsgraf v. Long Island Railroad (N.Y. 1928) — The proximate-cause anchor; taught in the same causation unit to distinguish cause-in-fact problems (Summers) from scope-of-liability problems (Palsgraf).