Summers v. Tice is a 1948 California Supreme Court decision that created the doctrine of alternative liability, which shifts the burden of proving causation to the defendants when two or more of them acted negligently and the plaintiff cannot tell which one caused the injury. The case grew out of a quail hunting accident in which two hunters fired at the same moment in the direction of a third, and the court refused to let both walk away just because the victim could not say which gun fired the pellet that hit him. It remains one of the most cited causation cases in American tort law.
The Hunting Accident Behind the Case
On November 20, 1945, Charles Summers went quail hunting on open range with Harold Tice and a companion named Simonson. Before they set out, Summers told both men to be careful and to stay in line with one another.1Justia. Summers v. Tice As the group moved through brush, Summers went up a hill, putting the three hunters at the points of a triangle. Both defendants could see him and knew where he was.
A quail flushed and rose about ten feet, flying between Summers and the two defendants. Tice and Simonson both fired their 12-gauge shotguns in the direction of the bird, which was also the direction of Summers. Each gun was loaded with 7½ size shot, and both men were about 75 yards away.1Justia. Summers v. Tice One pellet struck Summers in the right eye, another in the upper lip. Because both shooters used identical ammunition from similar distances and fired at the same moment, nothing in the physical evidence tied a particular pellet to a particular gun.
Why the Case Was Hard to Prove
Negligence normally requires the plaintiff to show that a specific defendant’s conduct caused the injury. Under the traditional but-for test, Summers had to prove that a particular pellet came from a particular gun. He could not. The pellet in his eye came from one of the two shotguns, but no evidence pointed to either one.
Applied strictly, that gap ends the case. If Summers accused Tice, Tice could point at Simonson. Simonson could do the same. Two negligent shooters would go free, and the only person who did nothing wrong would carry the full cost of a serious eye injury. The trial court refused that result. It found both defendants negligent, found Summers free of contributory negligence, and entered judgment against both.1Justia. Summers v. Tice Both appealed.
What the California Supreme Court Held
The California Supreme Court affirmed and used the case to reshape how causation works when multiple negligent defendants make identification impossible. Justice Carter, writing for the court, said both defendants were wrongdoers, both were negligent toward the plaintiff, and between them they created the situation. It should fall on each of them to clear himself if he can. The court described Summers as having been placed in an “unfair position,” and noted that if one defendant could escape liability on the ground that the plaintiff could not prove which fired the shot, so could the other, leaving the victim with no remedy at all.1Justia. Summers v. Tice
The court also observed that defendants are ordinarily “in a far better position to offer evidence to determine which one caused the injury.” Tice and Simonson knew their own angles, positions, and timing. Summers, in the moment he was being hit, was not gathering ballistics data. Asking him to reconstruct two simultaneous shotgun blasts was asking for the impossible.
The holding treated the two hunters as joint tortfeasors, each liable for the whole judgment. The court drew on a broader rationale for joint liability: the “practical unfairness of denying the injured person redress simply because he cannot prove how much damage each did, when it is certain that between them they did all.”1Justia. Summers v. Tice Summers could collect the full award from either defendant, and the defendants would have to sort out apportionment between themselves.
When Alternative Liability Applies
The doctrine is not a general workaround for thin evidence. Courts apply it narrowly, and a plaintiff must satisfy each of the following before the burden shifts:
- All possible wrongdoers are named as defendants. If a potential tortfeasor is missing, the actual wrongdoer may not be in court at all, which defeats the point of shifting the burden.
- Every defendant acted negligently toward the plaintiff. A defendant who behaved safely cannot be swept in because someone else was reckless.
- The harm was in fact caused by one of the defendants. The doctrine addresses the question of which defendant caused the injury, not whether any of them did.
- The plaintiff’s inability to identify the cause is not the plaintiff’s fault. The evidentiary gap must come from the situation the defendants created, not from a failure to investigate.
When any of those elements is missing, courts revert to the ordinary causation rule and require the plaintiff to identify the responsible defendant.
Codification and Later Expansion
The American Law Institute adopted the principle in the Restatement (Second) of Torts § 433B(3), which states that where two or more actors engage in tortious conduct and the plaintiff proves one of them caused the harm but cannot identify which, the burden falls on each actor to prove he did not cause it. That standardized formulation helped courts in other states adopt the rule, though adoption is not universal and some jurisdictions apply it more cautiously than others.
The framework worked well with two hunters. It broke down when the California Supreme Court faced Sindell v. Abbott Laboratories in 1980. The plaintiff’s mother had taken diethylstilbestrol (DES) during pregnancy, hundreds of manufacturers had produced the drug from an identical formula, and injuries did not appear until years later. Naming every possible manufacturer was impossible.2Justia. Sindell v. Abbott Laboratories
The court’s answer was market share liability. The plaintiff had to join manufacturers representing a “substantial share” of the relevant market, and each defendant would then pay damages in proportion to its market share unless it could prove it did not make the product that caused the injury.2Justia. Sindell v. Abbott Laboratories The court called this a “modification of the rule of Summers.” The key change was the shift from full joint liability to proportional liability. In a two-hunter accident, one defendant definitely caused everything, so full liability makes sense. In a case with dozens of manufacturers, proportional shares better match the probability that any given company made the harmful pill.
What Joint and Several Liability Means for Plaintiffs
Because alternative liability under Summers is joint and several, the plaintiff can collect the entire judgment from whichever defendant has assets. That matters most when a defendant is insolvent. In that situation, the solvent defendant absorbs the full obligation instead of the plaintiff receiving only partial compensation.
Many states have modified joint and several liability through tort reform, sometimes limiting it to defendants above a minimum percentage of fault and sometimes replacing it with several-only liability. Where fractional liability applies, a defendant may owe only its assigned share, and an insolvent co-defendant’s share can fall on the plaintiff rather than the other wrongdoer. The protective effect of the Summers rule for injured plaintiffs therefore looks different depending on the jurisdiction.
The larger principle from the case has traveled well beyond quail hunting. Wherever several parties act negligently and their combined conduct makes it impossible to trace a specific injury to a specific source, the same reasoning applies: between an innocent plaintiff and a group of proven wrongdoers, the wrongdoers should carry the risk of the uncertainty they created. That reasoning has shaped how American courts approach causation in toxic exposure cases, pharmaceutical litigation, and other contexts where the specific source of harm cannot be identified through no fault of the person who was hurt.