What does the legal theory of estoppel aim to prevent?

The legal theory of estoppel is aimed at preventing denial of past statements or actions. It is grounded in fairness and the principle that a person should not be allowed to contradict something that they have previously established as a fact. For instance, if someone has made a promise or representation that another party relied upon, that person cannot later assert something contrary to what was previously stated or implied, especially if it would harm the other party who relied on those statements.

Estoppel is commonly invoked in various legal contexts, such as contract law and property disputes, where one party's reliance on a previous statement or action has created certain expectations or has caused harm if changed. Thus, estoppel serves to uphold consistency and protect parties from surprises in legal transactions or relationships that arise from an established understanding.

In contrast, other choices relate to different legal concepts. Changing ownership of land pertains to property law issues involving transfer rights; use of land without permission is more about trespass or property rights; and disputing a contract after signing usually involves specific legal principles surrounding contracts, such as waiver or capacity, rather than estoppel itself.