Sumption in Virgin Atlantic Airways Ltd v Zodiac Seats UK Ltd

Res judicata is a portmanteau term comprising distinct doctrines (cause of action estoppel, issue estoppel, merger and the rule in Henderson v Henderson); cause of action estoppel is absolute only for points actually decided and does not bar reliance on later-arising facts, so a defendant whose patent is subsequently revoked or amended with retrospective effect may rely on that to defeat an inquiry as to damages even though liability was earlier established.