What is 'Res Judicata'? | A Guide

What does res judicata mean?

The term “res judicata” also known as claim preclusion, is the Latin term for “a matter (already) judged”.

Doctrine of Res Judicata

The doctrine of res judicata prohibits reopening an issue which has already been decided between the parties by a competent court or tribunal. Case law provides for finality in proceedings and to protect a party from being harassed by successive actions by another party when the issues between them were determined in the first proceedings (Henderson v Henderson (1843) 3 Hare 100).

Interest Republicae ut sit Finis Litium

The maxim “interest republicae ut sit finis litium” translates as “it is in the public interest that there be an end to litigation”.

This maxim is routinely applied by Irish courts to ensure inter alia that attempts by new litigation (rather than by appeal) to attack collaterally a court’s findings will generally be prevented as an abuse of process. 

Cause of Action Estoppel

“Cause of action estoppel is defined in “Res Judicata and Double Jeopardy” by Paul A. McDermott (Butterworth 1999, at p57):-

“The term “cause of action” estoppel signifies the estoppel which arises between parties by reason of a judgment given in favour of one and against the other with respect to the cause of action set up in the first proceedings. Its operation prevents a party to an action from asserting or denying as against the other party the existence of a cause of action, the existence or non-existence of which has already determined by a court of competent jurisdiction in previous litigation between the parties. To succeed in such a plea it must be shown that the cause of action in the earlier action is the same as that raised in the second action; D v C [1984] ILRM 173 at 192 (HC).”

A concise definition of cause of action estoppel (and issue estoppel) as offered by Blayney J. in Gilroy v McLoughlin [1989] ILRM 133, at 136, as follows: -

“In cause of issue estoppel the question is whether a plaintiff is estopped from bringing a particular action by reason of having brought a similar action previously against the same party, while issue estoppel is concerned with whether a particular issue has previously been determined between the same parties by a Court of competent jurisdiction”.

The underlying rationale for the doctrine was explained by Keane J (as he then was) in Dublin Corporation v Building and Allied Trades Union [1996] 2 I.L.R.M 547 as follows:

“The justification of the doctrine is normally found in the maxim interest reipublicae ut sit finis litium and it is important to bear in mind that the public interest referred to reflects, in part at least, the interest of all citizens who resort to litigation in obtaining a final and conclusive determination of their disputes. However severe the stresses of litigation may be for the parties involved — the anxiety, the delays, the costs, the public and painful nature of the process — there is at least the comfort that at some stage finality is reached. Save in those exceptional cases where his opponent can prove that the judgment was procured by fraud, the successful litigant can sleep easily in the knowledge that he need never return to court again.”

Examples of Res Judicata

In The National Museum of Ireland -v- Minister for Social Protection[2016] IEHC 135 it was held that was no issue of estoppel and/or res judicata arises in respect of a decision under the Social Welfare Acts and a claim under employment legislation that is brought to the Workplace Relations Commission (WRC). The Labour Court therefore found that a decision regarding the complainant’s employment status under the Social Welfare Acts, while it may be persuasive, had no effect on a decision of an Adjudication Officer.

In A College Employee v A Third Level College (ADJ-00026088), the complaint was seeking adjudication by the WRC under Section 14 of the Protection of Employees (Fixed-Term Work) Act, 2003. The respondent raised a preliminary issue on the complaint asserting that the matters in the complaint were covered by the res judicata rule as the complaint had been the subject of a previous WRC hearing. That hearing related to complaints under the both the Protection of Employees (Fixed Term Work) Act 2003 and the Industrial Relations Act 1969. While no decision had been issued, at the date of the hearing but had since, it was determined that the complainant could not re-litigate the same issues.

In A HR Administrator v A Renewable Energy Company (ADJ-00020154), the WRC was satisfied that there was no expressed impediment in either the Employment Equality Acts or the Parental Leave Act to debar two complaints being considered by the WRC. The Adjudication Officer was satisfied that the WRC was originally established as a merger of the employment rights bodies and with it help solve the possible forum shopping that it could be said arose in the likes of Jahan Company v Power. The two within complaints were lodged with the WRC for adjudication within days of each other, they had been associated and ran together, and they were heard together. There was no previous adjudication made on either complaint heretofore. The facts of the complaints were intertwined, however, the complainant was claiming two different legal issues. One was a breach of her employment rights as prescribed under the Parental Leave Act 1998 and the other was discrimination under the gender and family status grounds under the Employment Equality Acts 1998-2015.