Legal Dictionary
Main Entry:
es·top·pelPronunciation:
e-'stä-p&lFunction:
nounEtymology: probably from Middle French
estoupail plug, stopper, from
estouper to stop up —see
ESTOP 1 : a bar to the use of contradictory words or acts in asserting a claim or right against another;
especially : EQUITABLE ESTOPPEL in this entry —compare
WAIVER
equitable estoppel : an estoppel that prevents a person from adopting a new position that contradicts a previous position maintained by words, silence, or actions when allowing the new position to be adopted would unfairly harm another person who has relied on the previous position to his or her loss called also
estoppel in pais NOTE: Traditionally equitable estoppel required that the original position was a misrepresentation which was being denied in the new position. Some jurisdictions retain the requirement of misrepresentation.
estoppel by deed : an estoppel precluding a person from denying the truth of any matter that he or she asserted in a deed esp. regarding his or her title to the property —compare
after-acquired title at
TITLE
estoppel by silence : an estoppel preventing a person from making an assertion to another's disadvantage when the person previously had the opportunity and duty to speak but failed to do so
estoppel in pais : EQUITABLE ESTOPPEL in this entry
file wrap·per estoppel : an estoppel in patent law barring an applicant who has acquiesced in the rejection of a broad claim in the application for a patent from later asserting that a claim deliberately more restricted is equivalent to the original claim called also
prosecution history estoppel
promissory estoppel : an estoppel that prevents a promisor from denying the existence of a promise when the promisee reasonably and foreseeably relies on the promise and to his or her loss acts or fails to act and suffers an injustice that can only be avoided by enforcement of the promise
prosecution his·to·ry estoppel : FILE WRAPPER ESTOPPEL in this entry
quasi estoppel : an equitable estoppel that does not require misrepresentation by one party nor reliance or ignorance by the other party
2 a : a bar to the relitigation of issues
collateral estoppel : estoppel by judgment barring the relitigation of issues litigated by the same parties on a different cause of action;
broadly : estoppel by judgment barring the relitigation of issues litigated by the same parties on a different or the same cause of action
direct estoppel : estoppel by judgment barring the relitigation of issues litigated by the same parties on the same cause of action
estoppel by judgment : a bar to the relitigation in a second action of issues already determined in a previous action;
especially : COLLATERAL ESTOPPEL in this entry called also
estoppel by verdict issue preclusion —see also
FORMER ADJUDICATION —compare
MERGER 4,
RES JUDICATA b : the affirmative defense of estoppel—
by estoppel : arising from the operation of estoppel
by estoppel>
[e-stop-uh
l] 
