Argument against the Legitimacy of the General Ethics Agreement

When the attorney has a client sign on a form or a fee agreement, it should be noted that he cannot argue against the document itself or the transaction in question:
“An attorney who drafted or participated in the preparation of a document, or who handled a transaction or participated in its handling, will not subsequently argue against the legitimacy of the document or transaction, nor will he represent a person whose case reasonably requires such a claim.”