Acquiescence

In law, acquiescence occurs when a person knowingly stands by without raising any objection to the infringement of his or her rights, while someone else unknowingly and without malice aforethought acts in a manner inconsistent with their rights. As a result of acquiescence, the person whose rights are infringed may lose the ability to make a legal claim against the infringer, or may be unable to obtain an injunction against continued infringement. The doctrine infers a form of "permission" that results from silence or passiveness over an extended period of time.
Overview.
Although not typically found in statutory law, the doctrine of acquiescence is well-supported by case law. One common context in which acquiescence is raised is when there is a dispute or disagreement over the location of a property line, followed by an extended period of time during which the parties respect a property line. Even if it is later discovered that the actual property line was in a different location, the long-term acquiescence to the incorrectly placed line may result in its becoming enforceable as the legal property line.
An example of the law of acquiescence occurred in a dispute between the State of Georgia and the State of South Carolina, in which the Supreme Court of the United States held that Georgia could no longer make any claim to an island in the Savannah River, despite the 1787 Treaty of Beaufort's assignment to the contrary. The court said that Georgia had knowingly allowed South Carolina to join the island as a peninsula to its own coast by dumping sand from dredging, and to then levy property taxes on it for decades. Georgia thereby lost the island-turned-peninsula by its own acquiescence, even though the treaty had given it all of the islands in the river.
Similar legal doctrines.
Doctrines similar to acquiescence include: