Due process
Collateral estoppel cases raise constitutional due process problems, particularly when it is applied to a party that did not participate in the original suit. Due process mandates that collateral estoppel not be applied to a party that has not litigated the issue in dispute, unless that party is in legal privity to a party that litigated it. In other words, every disputant is entitled to a day in court and cannot ordinarily be bound by the negative result of another disputant's suit, even if that other disputant had exactly the same legal and factual arguments.