Issue preclusion is a common law doctrine that prevents a party to a lawsuit from re-litigating an issue once it has been decided in a previous case.  In other words, a person or party who seeks to re-litigate any already decided issue is collaterally stopped from doing so.  Issue preclusion was formerly known as collateral estoppel.  The rationale behind the doctrine is prevention of legal harassment and prevention of abuse of legal resources.  Three elements must be satisfied in order to apply the doctrine.

• There must be a prior litigation in which the identical issue was brought before the court.
• The issue must be actually litigated in the first judicial proceeding, and the party against whom collateral estoppel is being asserted had a full and fair opportunity to litigate the issue in the first judicial proceeding.
• The issue must necessarily be decided and rendered as a necessary part of the court’s final judgment.

However, collateral estoppel does not prevent future litigation over issues not actually raised in the original judicial proceeding, even if the issues could have been raised.  Moreover, it is not necessary that the second judicial proceeding should be based on the same of action as of the first judicial proceeding.  The old rule that only the actual parties to the first judicial proceeding may be bound by the court’s findings/decision on the issue has been abolished.  A person may not be bound by issue preclusion unless he was bound by prior litigation.  However, any person may raise an issue preclusion defense (Non mutual defensive collateral estoppel) whether or not s/he is bound by the prior judgment.