Albert Barnes Commentary Esther 1:19

"If it please the king, let there go forth a royal commandment from him, and let it be written among the laws of the Persians and the Medes, that it be not altered, that Vashti come no more before king Ahasuerus; and let the king give her royal estate unto another that is better than she." — Esther 1:19 (ASV)

That it be not altered - Compare the margin reference. This was the theory. Practically, the monarch, if he chose, could always dispense with the law. It was therefore quite within his power to restore Vashti to her queenly dignity notwithstanding the present decree, if he wished.