- Issue preclusion prevents relitigation of particular issues of fact or law that have been actually litigated and previously determined. (Narrower than claim preclusion; does not preclude the whole claim necessarily, just the same issue) - An issue will be precluded if: (1) There was a valid final judgment on the merits in the first case (2) Same Issue: The same issue was actually litigated and determined in the first case (3) Issue was Essential to the Judgment: Judgment would have been different in the first case absent litigation of this issue --Restatement 2d Judgments: none precluded, unless affirmed on appeal --Restatement 1st Judgments: all precluded (4) Asserted against ACTUAL party to previous case There are 2 views on who may assert issue preclusion: (1) Mutuality (traditional view): Only parties to prior litigation can assert issue preclusion (2) Non-mutuality (modern view): Issue preclusion may be asserted by those who were not parties in prior litigation