- Can ONLY use on someone who has lost in prior case - Can come up in two ways: Non-mutual defensive and non-mutual offensive - Parklane: Trial judge may apply non-mutual offensive issue preclusion except where 1) plaintiff easily could have joined in earlier suit 2) application of issue preclusion would be unfair to defendant -- Examples: low stakes/incentives in first case, inconsistent judgments, different procedural opportunities in second case that likely would cause a different result