To Re-Litigate, Or Not To Re-Litigate, That Is The Question

What is res judicata?

Res judicata is the doctrine which prevents a party from re-litigating an issue or a defence which has already been determined (known as cause of action estoppel or issue estoppel) or which could have previously been litigated (the principle established in the 1843 case of Henderson v Henderson). There is a degree of confusion in this area of law and, although a number of recent cases, explored in more detail below, have sought to bring clarity, Claimants and Defendants alike need to be alert to the practical application of res judicata. Claimants seeking to plead an issue or cause of action that has either already been litigated or should have been raised in earlier proceedings, run the risk of having to defend a strike out action and possible adverse costs orders. Equally, Defendants need to understand when it is appropriate to raise a res judicata challenge.