The term acquiescence is used to describe an act of a person in knowingly standing by without raising any objection to infringement of his rights, when someone else is unknowingly and honestly putting in his resources under the impression that the said rights actually belong to him. These results in a situation wherein the person whose rights are infringed cannot anymore make a claim against the infringer or succeed in an injunction suit due to his conduct. Therefore acquiescence is the acceptance or agreement by keeping quiet or by not making objections.
Estoppel on the other hand refers to the preclusion of a person from denying or asserting anything to the contrary of that which has been established as the truth. This may either be by the acts of judicial or legislative officers, or by a person’s own deed, acts, or representations, either express or implied.
Estoppel in the context of encroachment usually occurs in case of structural encroachment. Structural encroachment is a concept in American real property law, in which a piece of real property hangs from one property over the property line of another landowner’s premises. The actual structure that encroaches might be a tree, bush, bay window, stairway, steps, stoop, garage, leaning fence, part of a building, etc. If the landowner permits such structural encroachment to remain in the property for a long time, s/he will have estopped their right to complain about the structure later.
In law, both acquiescence and estoppel are factors that bar an encroachment action.[i]
When a landowner does not complain for a long time about an encroachment to his property, under the principles of acquiescence as well as under estoppel, subsequently, s/he loses the right to complain. Therefore in the case of City of Eustis v. Firster[ii], it was held that a plaintiff is not entitled to mandatory injunction for removal of boathouses and piers built by city more than 25 years earlier where condition existed when plaintiff acquired his or her property and he or she did nothing about it for 10 years.
Also, in the case of Bright v. Michel[iii], it was held that equitable estoppel prevented mandatory injunction where plaintiffs lent defendants money to construct encroachments, observed encroachments being built, and voiced no objection thereto until after encroachments were completed and bad feeling arose, and where defendants thought that they were not encroaching.
[i] Granberry v. Jones, 188 Tenn. 51, 216 S.W.2d 721 (1949).
[ii] 113 So. 2d 260 (Fla. Dist. Ct. App. 2d Dist. 1959).
[iii] 242 Miss. 738, 137 So. 2d 155 (1962).