⚡ 10-Second Rule
Once a question was truly fought, decided, and mattered to the result, the loser can't re-fight that exact question later.
🧒 ELI-10 Scene
Mia and her brother Theo argued about who is taller. Grandpa measured them both against the door frame, marked it in pencil, and declared Theo taller. Mia was there, argued hard, and lost fair and square. A week later they fight over the front seat, and Mia demands a re-measure. Grandpa points at the pencil mark. That question is finished — for Mia. But when cousin Leah visits and claims she's tallest, Leah gets her own measurement. Leah never stood at that door frame.
⚖️ Actual Rule
Issue preclusion (collateral estoppel) bars relitigation of an issue when: (1) the same issue was (2) actually litigated and determined in a prior action, (3) the determination was essential to a valid final judgment, and (4) preclusion is asserted against a party — or one in privity with a party — to the prior action who had a full and fair opportunity to litigate the issue. Due process forbids binding a person who was never a party or privy, so preclusion runs only against someone who already had their day in court. Federal courts have abandoned strict mutuality: a stranger to the first judgment may sometimes use it. Nonmutual defensive use — a new defendant shielding itself with the plaintiff's earlier loss — is permitted under Blonder-Tongue Laboratories, Inc. v. University of Illinois Foundation, 402 U.S. 313 (1971). Nonmutual offensive use — a new plaintiff wielding the defendant's earlier loss — is allowed in the trial court's discretion under Parklane Hosiery Co. v. Shore, 439 U.S. 322 (1979), considering whether the plaintiff could easily have joined the first action, whether the defendant had a full incentive to litigate it, whether the judgment conflicts with other judgments, and whether the second action offers procedural opportunities the first lacked.
ELI-10 translation: a fully fought, decided, result-driving question stays decided — but only against someone who was actually in that first fight.
🔍 Ask These Questions
- Is it the same exact issue in both cases? (Same question about the same event — not just a lookalike?)
- Was the issue actually litigated and decided? (Did both sides really fight it? Default judgments and settlements decide nothing.)
- Was the finding essential to the judgment? (Would the result change without it? Extra side-comments don't count.)
- Is preclusion aimed at someone who was a party or privy with a full and fair chance? (You can only hold the pencil mark against someone who stood at the door frame.)
- If the user is a stranger to case one, which direction is it? (A new defendant blocking with an old loss is usually fine.)
- If it's a new plaintiff attacking, run the Parklane fairness factors. (Could they have joined earlier? Did the loser fight hard? Are the old answers consistent?)
⚠️ Bar Trap
Exam language: Examiners run issue preclusion against a litigant who was never a party or privy in the first action — often a co-victim of the same accident — inviting you to bind a stranger to a judgment in violation of due process. The offensive variant hands a new plaintiff a prior defense verdict or an easily joinable prior suit and dares you to overlook the Parklane discretion factors.
ELI-10: Check who actually stood at the door frame. A person who never got to argue the question can never be stuck with the answer.
🧪 Question
A charter bus skidded off a highway, injuring several passengers. Passenger Ana sued the bus company in federal court, alleging negligent maintenance of the brakes. After a full trial, the jury found the company was not negligent, and the court entered final judgment for the company. Passenger Ben, injured in the same accident, then filed his own negligence action against the company in the same court, likewise alleging negligent brake maintenance. The company moved for summary judgment, arguing that the prior finding of no negligence precludes Ben from litigating the issue.
How should the court rule on the motion?
(A) Grant it, because the negligence issue was actually litigated and decided in the first action. (B) Grant it, because both suits arise from the same transaction and the first ended in a final judgment on the merits. (C) Deny it, because Ben was not a party to the first action and has never had a full and fair opportunity to litigate the issue. (D) Deny it, because a jury finding of no negligence is never entitled to preclusive effect.
Answer: (C). Issue preclusion may be asserted only against someone who was a party or privy in the prior action. Ben was a stranger to Ana's suit, so binding him to its outcome would deny him due process, no matter how thoroughly the issue was tried.
💡 Why the Wrong Answers Are Wrong
- (A) satisfies the actually-litigated element but ignores the against-whom element; every element must hold, and this one fails.
- (B) recites claim preclusion, which also fails here because Ben's claim is his own — he was not a party to Ana's case.
- (D) is overbroad; fully litigated jury findings routinely preclude, just only against the parties who litigated them.
- ELI-10: The misconception is treating a settled question as settled for everyone. It's settled only for the people who were in the room fighting it.
