Peter Ferrer, Andy Thorp and Olga Osadchaya consider the limitations of the doctrine of merger
A number of tools exist to prevent abuse of court process and ensure matters properly and finally determined by a competent court do not become subject to re-litigation. These fall under the umbrella of res judicata, encompassing concepts such as cause of action estoppel and issue estoppel, the rule in Henderson v Henderson (1843) 3 Hare 100, and the doctrine of merger.
The case
A recent decision of the English Court of Appeal in Zavarco PLC v Nasir [2021] EWCA Civ 1217 considers the long-standing doctrine of merger, and confirming unanimously it does not apply to purely declaratory relief. In ordinary circumstances, the doctrine operates to extinguish a cause of action upon its determina...