A more thorough explanation:

Estoppel by deed is a legal principle that prevents someone from arguing in court a position that contradicts what they stated in a previous deed. This doctrine is commonly applied in cases where a person sells property they do not own and later becomes involved in a dispute over that property.

For example, let's say John sells fifty acres of land to Parker for $200,000. However, John only owns thirty acres of the property, and the other twenty acres belong to someone else. In this case, Parker would only legally own the thirty acres that John owned. Even though John knows that Parker does not own the other twenty acres, he cannot argue in court that Parker does not own them because he already sold the property to Parker.

Another example of estoppel by deed could be a situation where a person signs a contract agreeing to certain terms and then tries to argue in court that the terms are unfair or invalid. In this case, the person would be estopped from making this argument because they already agreed to the terms in the contract.

Overall, estoppel by deed is a legal principle that prevents people from contradicting themselves in court and helps to ensure that property rights and contractual agreements are respected.