That which ought to have been done, is to be regarded as done, in favor of him to whom, and against him from whom, performance is due.

Explanation

(English-origin maxim.) Equity treats as done what ought to have been done. An agreement for valuable consideration is treated as executed from the date performance was due. Money agreed to be laid out in land is treated as real estate; land contracted to be sold is treated as money.

Where this applies

• A seller agrees to convey land to a buyer, dies before closing, and equity treats the land as already belonging to the buyer because the sale ought to have been completed.
• A man contracts to invest his money in real estate but dies before the purchase, and equity treats his money as if it had already been converted into land for inheritance purposes.
• A builder is owed payment for completed work but the client delays, and the court treats the payment as already made in the builder's favor because it ought to have been done.