How do you spell estapol?

The legal term is spelled "estoppel" and prevents legal denial or revocation once facts are established or actions have been taken. One example is that a litigant cannot claim that errors of his own warrant a lawsuit against someone else. A party may be estopped (prevented) from legal action in many circumstances.

(Collateral estoppel also prevents another suit for the same cause once it has been adjudicated. This does not prevent another party from suing for the same reason or action.)