Res judicata and estoppel
Res judicata under Sn.ll, is based on public policy. It is essentially procedural. Based conduct of parties, or on "Nemo dabet bix vexari" (No one should be vexed twice) to put an end to litigious tendency. What is barred in the second suit on the same cause of action?
Between the same parties and subject to other conditions of Sn.ll.
Res judicata ousts the juris diction of the court in the second suit.
Deals with jurisdiction of the second court itself and bars it from exercising jurisdiction.
Estoppel as per Sn.115 of Evidence Act is by conduct of parties, or agreement or estoppel in pais.
This is essentially a rule of evidence. It is based on the rule that if a person induces another to alter his situation, he cannot take advantage of such altered situation. He will not be allowed to contradict himself.
Estoppel shuts the mouth of the party from blowing hot and cold in the same breath.
This is by a party and hence he is prevented from going back on his earlier statement.